Anything can be powergamed in a sense, Jaeden. That does not warrant that you should -1 this. The guy seems to have put a lot of effort into this. As others already said, the possession and what not is already being used, this is just some lore or the sorts to make it less questionable, etc. The ghosts, whether they have a certain leader or someone who administrates those who play as ghosts, should be able to handle any powergamers or the like.
Over-all, I like it. +1