diff --git a/app/controllers/admin/campaigns_controller.rb b/app/controllers/admin/campaigns_controller.rb
index de09a520..2f39958a 100644
--- a/app/controllers/admin/campaigns_controller.rb
+++ b/app/controllers/admin/campaigns_controller.rb
@@ -12,11 +12,11 @@ module Admin
       @campaign.attributes = params[:campaign]
 
       if @conference.save
-        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title),
-                    notice: 'Campaign successfully created.')
+        flash[:notice] = 'Campaign successfully created.'
+        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title))
       else
-	flash[:error] = 'Campaign creation failed. ' + @campaign.errors.full_messages.to_sentence
-	render action: 'new'
+        flash[:error] = 'Campaign creation failed. ' + @campaign.errors.full_messages.to_sentence
+        render action: 'new'
       end
     end
 
@@ -26,23 +26,22 @@ module Admin
 
     def update
       if @campaign.update_attributes(params[:campaign])
-        redirect_to(admin_conference_campaigns_path(
-                        conference_id: @conference.short_title),
-                    notice: "Campaign '#{@campaign.name}' successfully updated.")
+        flash[:notice] = "Campaign '#{@campaign.name}' successfully updated."
+        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title))
       else
-	flash[:error] = 'Campaign update failed. ' + @campaign.errors.full_messages.to_sentence
-	render action: 'edit'
+        flash[:error] = "Campaign update failed.  #{@campaign.errors.full_messages.to_sentence}"
+        render action: 'edit'
       end
     end
 
     def destroy
       if @campaign.destroy
-        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title),
-                    notice: "Campaign '#{@campaign.name}' successfully deleted.")
+        flash[:notice] = "Campaign '#{@campaign.name}' successfully deleted."
+        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title))
       else
-        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title),
-                    alert: "Delete of Campaign for #{@conference.short_title} failed." \
-                    "#{@campaign.errors.full_messages.join('. ')}.")
+        flash[:error] = "Delete of Campaign for #{@conference.short_title} failed." \
+                    "#{@campaign.errors.full_messages.join('. ')}."
+        redirect_to(admin_conference_campaigns_path(conference_id: @conference.short_title))
       end
     end
   end
diff --git a/app/controllers/admin/difficulty_levels_controller.rb b/app/controllers/admin/difficulty_levels_controller.rb
index 70957f79..8ee5edc1 100644
--- a/app/controllers/admin/difficulty_levels_controller.rb
+++ b/app/controllers/admin/difficulty_levels_controller.rb
@@ -16,8 +16,8 @@ module Admin
     def create
       @difficulty_level = @conference.difficulty_levels.new(difficulty_level_params)
       if @difficulty_level.save
-        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title),
-                    notice: 'Difficulty level successfully created.')
+        flash[:notice] = 'Difficulty level successfully created.'
+        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Creating difficulty level failed: #{@difficulty_level.errors.full_messages.join('. ')}."
         render :new
@@ -26,9 +26,8 @@ module Admin
 
     def update
       if @difficulty_level.update_attributes(difficulty_level_params)
-        redirect_to(admin_conference_difficulty_levels_path(
-                    conference_id: @conference.short_title),
-                    notice: 'Difficulty level successfully updated.')
+        flash[:notice] = 'Difficulty level successfully updated.'
+        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Update difficulty level failed: #{@difficulty_level.errors.full_messages.join('. ')}."
         render :edit
@@ -37,12 +36,12 @@ module Admin
 
     def destroy
       if @difficulty_level.destroy
-        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title),
-                    notice: 'Difficulty level successfully deleted.')
+        flash[:notice] = 'Difficulty level successfully deleted.'
+        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title))
       else
-        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title),
-                    error: 'Deleting difficulty level type failed! ' \
-                    "#{@difficulty_level.errors.full_messages.join('. ')}.")
+        flash[:error] = 'Deleting difficulty level type failed! ' \
+        "#{@difficulty_level.errors.full_messages.join('. ')}."
+        redirect_to(admin_conference_difficulty_levels_path(conference_id: @conference.short_title))
       end
     end
 
diff --git a/app/controllers/admin/event_types_controller.rb b/app/controllers/admin/event_types_controller.rb
index 85d1ff6b..8f2cf042 100644
--- a/app/controllers/admin/event_types_controller.rb
+++ b/app/controllers/admin/event_types_controller.rb
@@ -16,8 +16,8 @@ module Admin
     def create
       @event_type = @conference.event_types.new(event_type_params)
       if @event_type.save
-        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title),
-                    notice: 'Event type successfully created.')
+        flash[:notice] = 'Event type successfully created.'
+        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Creating event type failed: #{@event_type.errors.full_messages.join('. ')}."
         render :new
@@ -26,9 +26,8 @@ module Admin
 
     def update
       if @event_type.update_attributes(event_type_params)
-        redirect_to(admin_conference_event_types_path(
-                    conference_id: @conference.short_title),
-                    notice: 'Event type successfully updated.')
+        flash[:notice] = 'Event type successfully updated.'
+        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Update event type failed: #{@event_type.errors.full_messages.join('. ')}."
         render :edit
@@ -37,12 +36,12 @@ module Admin
 
     def destroy
       if @event_type.destroy
-        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title),
-                    notice: 'Event type successfully deleted.')
+        flash[:notice] = 'Event type successfully deleted.'
+        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title))
       else
-        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title),
-                    error: 'Destroying event type failed! ' \
-                    "#{@event_type.errors.full_messages.join('. ')}.")
+        flash[:error] = 'Destroying event type failed! ' \
+        "#{@event_type.errors.full_messages.join('. ')}."
+        redirect_to(admin_conference_event_types_path(conference_id: @conference.short_title))
       end
     end
 
diff --git a/app/controllers/admin/rooms_controller.rb b/app/controllers/admin/rooms_controller.rb
index fcf707cb..0b6b53c3 100644
--- a/app/controllers/admin/rooms_controller.rb
+++ b/app/controllers/admin/rooms_controller.rb
@@ -16,8 +16,8 @@ module Admin
     def create
       @room = @conference.rooms.new(room_params)
       if @room.save
-        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title),
-                    notice: 'Room successfully created.')
+        flash[:notice] = 'Room successfully created.'
+        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Creating Room failed: #{@room.errors.full_messages.join('. ')}."
         render :new
@@ -26,9 +26,8 @@ module Admin
 
     def update
       if @room.update_attributes(room_params)
-        redirect_to(admin_conference_rooms_path(
-                    conference_id: @conference.short_title),
-                    notice: 'Room successfully updated.')
+        flash[:notice] = 'Room successfully updated.'
+        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Update Room failed: #{@room.errors.full_messages.join('. ')}."
         render :edit
@@ -37,12 +36,11 @@ module Admin
 
     def destroy
       if @room.destroy
-        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title),
-                    notice: 'Room successfully deleted.')
+        flash[:notice] = 'Room successfully deleted.'
+        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title))
       else
-        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title),
-                    error: 'Destroying room failed! ' \
-                    "#{@room.errors.full_messages.join('. ')}.")
+        flash[:error] = "Destroying room failed! #{@room.errors.full_messages.join('. ')}."
+        redirect_to(admin_conference_rooms_path(conference_id: @conference.short_title))
       end
     end
 
diff --git a/app/controllers/admin/tracks_controller.rb b/app/controllers/admin/tracks_controller.rb
index 13d6870f..438b3dd0 100644
--- a/app/controllers/admin/tracks_controller.rb
+++ b/app/controllers/admin/tracks_controller.rb
@@ -19,8 +19,8 @@ module Admin
     def create
       @track = @conference.tracks.new(track_params)
       if @track.save
-        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title),
-                    notice: 'Track successfully created.')
+        flash[:notice] = 'Track successfully created.'
+        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Creating Track failed: #{@track.errors.full_messages.join('. ')}."
         render :new
@@ -31,8 +31,8 @@ module Admin
 
     def update
       if @track.update_attributes(track_params)
-        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title),
-                    notice: 'Track successfully updated.')
+        flash[:notice] = 'Track successfully updated.'
+        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title))
       else
         flash[:error] = "Track update failed: #{@track.errors.full_messages.join('. ')}."
         render :edit
@@ -41,12 +41,11 @@ module Admin
 
     def destroy
       if @track.destroy
-        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title),
-                    notice: 'Track successfully deleted.')
+        flash[:notice] = 'Track successfully deleted.'
+        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title))
       else
-        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title),
-                    error: 'Track couldn\'t be deleted.' \
-                    "#{@track.errors.full_messages.join('. ')}.")
+        flash[:error] = "Track couldn't be deleted. #{@track.errors.full_messages.join('. ')}."
+        redirect_to(admin_conference_tracks_path(conference_id: @conference.short_title))
       end
     end
 
diff --git a/app/models/campaign.rb b/app/models/campaign.rb
index 77ff94f2..469f3433 100644
--- a/app/models/campaign.rb
+++ b/app/models/campaign.rb
@@ -4,7 +4,7 @@ class Campaign < ActiveRecord::Base
 
   validates :name, :utm_campaign, presence: true
 
-  has_many :targets
+  has_many :targets, dependent: :nullify
   belongs_to :conference
 
   ##
diff --git a/app/models/conference.rb b/app/models/conference.rb
index 5af417d7..5c1ae0c2 100644
--- a/app/models/conference.rb
+++ b/app/models/conference.rb
@@ -31,7 +31,7 @@ class Conference < ActiveRecord::Base
   has_one :call_for_paper, dependent: :destroy
   has_one :venue, dependent: :destroy
   has_many :social_events, dependent: :destroy
-  has_many :ticket_purchases
+  has_many :ticket_purchases, dependent: :destroy
   has_many :supporters, through: :ticket_purchases, source: :user
   has_many :tickets, dependent: :destroy
   has_many :dietary_choices, dependent: :destroy
diff --git a/app/models/difficulty_level.rb b/app/models/difficulty_level.rb
index b230c07f..36ec38c8 100644
--- a/app/models/difficulty_level.rb
+++ b/app/models/difficulty_level.rb
@@ -2,7 +2,7 @@ class DifficultyLevel < ActiveRecord::Base
   attr_accessible :title, :description, :color, :conference_id
 
   belongs_to :conference
-  has_many :events
+  has_many :events, dependent: :nullify
 
   validates :title, presence: true
 end
diff --git a/app/models/event.rb b/app/models/event.rb
index c24506c1..81b4103e 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -29,7 +29,7 @@ class Event < ActiveRecord::Base
   before_create :generate_guid
 
   validate :abstract_limit
-  validate :before_end_of_conference
+  validate :before_end_of_conference, on: :create
   validate :name_and_biography_exists
   validates :title, presence: true
   validates :abstract, presence: true
diff --git a/app/models/event_type.rb b/app/models/event_type.rb
index a2204985..2430b76e 100644
--- a/app/models/event_type.rb
+++ b/app/models/event_type.rb
@@ -3,6 +3,7 @@ class EventType < ActiveRecord::Base
                   :conference_id
 
   belongs_to :conference
+  has_many :events, dependent: :restrict_with_error
 
   validates :title, presence: true
   validates :length, numericality: {greater_than: 0}
diff --git a/app/models/room.rb b/app/models/room.rb
index cf59e39b..93f57a4b 100644
--- a/app/models/room.rb
+++ b/app/models/room.rb
@@ -2,7 +2,7 @@ class Room < ActiveRecord::Base
   attr_accessible :name, :size, :conference_id
 
   belongs_to :conference
-  has_many :events
+  has_many :events, dependent: :nullify
 
   before_create :generate_guid
 
diff --git a/app/models/ticket.rb b/app/models/ticket.rb
index 45558a5b..54c54667 100644
--- a/app/models/ticket.rb
+++ b/app/models/ticket.rb
@@ -1,6 +1,6 @@
 class Ticket < ActiveRecord::Base
   belongs_to :conference
-  has_many :ticket_purchases
+  has_many :ticket_purchases, dependent: :destroy
   has_many :buyers, -> { distinct }, through: :ticket_purchases, source: :user
 
   attr_accessible :conference, :title, :url, :description, :conference_id, :price_cents, :price_currency, :price
diff --git a/app/models/track.rb b/app/models/track.rb
index bd48e58d..7f8cfbcb 100644
--- a/app/models/track.rb
+++ b/app/models/track.rb
@@ -1,7 +1,7 @@
 class Track < ActiveRecord::Base
   attr_accessible :name, :description, :color, :conference_id
   belongs_to :conference
-  has_many :events
+  has_many :events, dependent: :nullify
 
   before_create :generate_guid
   validates :name, presence: true
diff --git a/app/models/user.rb b/app/models/user.rb
index b205ae4c..6214d07a 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -38,7 +38,7 @@ class User < ActiveRecord::Base
   has_many :event_users, dependent: :destroy
   has_many :events, -> { uniq }, through: :event_users
   has_many :registrations, dependent: :destroy
-  has_many :ticket_purchases
+  has_many :ticket_purchases, dependent: :destroy
   has_many :tickets, through: :ticket_purchases, source: :ticket
   has_many :votes, dependent: :destroy
   has_many :voted_events, through: :votes, source: :events
diff --git a/app/views/admin/campaigns/_form.html.haml b/app/views/admin/campaigns/_form.html.haml
index c65f49f1..507cb540 100644
--- a/app/views/admin/campaigns/_form.html.haml
+++ b/app/views/admin/campaigns/_form.html.haml
@@ -19,6 +19,6 @@
           = f.input :utm_term, label: 'Term', hint: 'Campaign keywords. E.g. marketing+conference+opensource'
           = f.input :utm_content, label: 'Content', hint: 'Used to track the different types of content that point to the same URL (A/B Test).'
         = f.inputs name: 'Targets' do
-          = f.input :targets
+          = f.input :targets, collection: @conference.targets
       %p.text-right
         = f.action :submit, as: :button, button_html: { class: 'btn btn-primary' }
diff --git a/app/views/admin/difficulty_levels/index.html.haml b/app/views/admin/difficulty_levels/index.html.haml
index f2668a71..1b02d446 100644
--- a/app/views/admin/difficulty_levels/index.html.haml
+++ b/app/views/admin/difficulty_levels/index.html.haml
@@ -27,7 +27,8 @@
                 = link_to 'Edit', edit_admin_conference_difficulty_level_path(@conference.short_title, difficulty_level.id),
                 method: :get, class: 'btn btn-primary'
                 = link_to 'Delete', admin_conference_difficulty_level_path(@conference.short_title, difficulty_level.id),
-                method: :delete, class: 'btn btn-danger', data: { confirm: "Do you really want to delete #{difficulty_level.title}?" }
+                method: :delete, class: 'btn btn-danger',
+                data: { confirm: "Do you really want to delete #{difficulty_level.title}? Attention: This difficulty level will be removed from all Events that have it set" }
 .row
   .col-md-12.text-right
     = link_to 'Add Difficulty Level', new_admin_conference_difficulty_level_path(@conference.short_title), class: 'btn btn-primary'
diff --git a/app/views/admin/rooms/index.html.haml b/app/views/admin/rooms/index.html.haml
index f9007a79..52f00f18 100644
--- a/app/views/admin/rooms/index.html.haml
+++ b/app/views/admin/rooms/index.html.haml
@@ -24,7 +24,8 @@
                 = link_to 'Edit', edit_admin_conference_room_path(@conference.short_title, room.id),
                 method: :get, class: 'btn btn-primary'
                 = link_to 'Delete', admin_conference_room_path(@conference.short_title, room.id),
-                method: :delete, class: 'btn btn-danger', data: { confirm: "Do you really want to delete #{room.name}?" }
+                method: :delete, class: 'btn btn-danger',
+                data: { confirm: "Do you really want to delete #{room.name}? Attention: This room will be removed from all Events that have it set"}
 .row
   .col-md-12.text-right
     = link_to 'Add Room', new_admin_conference_room_path(@conference.short_title), class: 'btn btn-primary'
diff --git a/app/views/admin/tickets/index.html.haml b/app/views/admin/tickets/index.html.haml
index 54b29754..acf6915f 100644
--- a/app/views/admin/tickets/index.html.haml
+++ b/app/views/admin/tickets/index.html.haml
@@ -31,7 +31,8 @@
                   = link_to 'Edit', edit_admin_conference_ticket_path(@conference.short_title, ticket.id),
                   method: :get, class: 'btn btn-primary'
                   = link_to 'Delete', admin_conference_ticket_path(@conference.short_title, ticket.id),
-                  method: :delete, class: 'btn btn-danger', data: { confirm: "Do you really want to delete the Ticket for #{ticket.title}?" }
+                  method: :delete, class: 'btn btn-danger',
+                  data: { confirm: "Do you really want to delete the Ticket for #{ticket.title}? Attention: All ticket purchases will be also deleted!" }
 .row
   .col-md-12
     = link_to 'Add Ticket', new_admin_conference_ticket_path, class: 'btn btn-success pull-right'
diff --git a/app/views/admin/tracks/index.html.haml b/app/views/admin/tracks/index.html.haml
index 986ea522..8ba3a41b 100644
--- a/app/views/admin/tracks/index.html.haml
+++ b/app/views/admin/tracks/index.html.haml
@@ -29,7 +29,8 @@
                 = link_to 'Edit', edit_admin_conference_track_path(@conference.short_title, track.id),
                 method: :get, class: 'btn btn-primary'
                 = link_to 'Delete', admin_conference_track_path(@conference.short_title, track.id),
-                method: :delete, class: 'btn btn-danger', data: { confirm: "Do you really want to delete #{track.name}?" }
+                method: :delete, class: 'btn btn-danger',
+                data: { confirm: "Do you really want to delete #{track.name}? Attention: This track will be removed from all Events that have it set" }
 .row
   .col-md-12.text-right
     = link_to 'New Track', new_admin_conference_track_path(@conference.short_title), class: 'btn btn-success'