I have had a mod idea brewing in the back of my head for months, and I have a few questions about what can and can't be done in the Creation Kit. The mod idea is for a large dungeon/maze type location, and a quest-line involving it)
(Note that I do not have Skyrim on PC yet, I play it on a friend's Xbox, although I am planning on buying it at some point)
Things I want to know (I'll explain them further down):

• Is it possible to check if the player has a power from a DLC is active (Dawnguard's Vampire Lord form), yet ensure that the mod is still playable without that DLC?
  
• Can I allow a wall to be passed through if that power is active? (so that a VL can pass through a wall of ice)
  
• Is it possible to take control of another NPC temporarily?
  
• Kill the player, but instead of a reload, the player suddenly appears in a ghostlike state? (the ghostlike state I know is possible (an effect that makes the player look like a ghost, and maybe some odd behaviours for certain interactions)
  
• place a fake corpse of a certain NPC and another of the player?

these questions are about some sections of the story and area. the first two are for a small easter egg, where players in VL form can pass through an ice wall like they are said to be able to do in the book Immortal Blood
the next is mostly out of curiosity, although I may consider it into the mod if possible
the last two are for a part of the story where the antagonist tries to bend you (and an NPC encountered in the story) to his will by using necromancy to kill and raise you as a ghost (but perhaps he is distracted or your soul is too powerful to control etc)
any help/thoughts/etc would be appreciated