With the 'Ally or Enemy' ability, is the host being aware of the fiend a requirement only for the bonus or for the penalty as well? (That is, can the fiend impose a profane penalty on someone who doesn't realize that the fiend is there?)

It could make a crossbow **** and fire (but not aim or load itself). Exerting control is itself a free action, though actually moving an object requires a move action.
The stars make the first sentence ambiguous. Was that meant to be a placeholder for something that you forgot to go back and change?

I'm actually not familiar with the original prestige class, but this update is really well done in my opinion. The class abilities that are similar in form to the Fiendish Codices, Heroes of Horror, Book of Vile Darkness, etc. work well and they lend themselves well to being applied to a possessing evil spirit. I think a class like this would be a good opponent for a campaign centered around the Spirit Shaman class (as well as the Sacred Exorcist you mentioned).