Does your character have any special resistances to the illusions or abilities that would make it more likely to fail? Nope! Illusify away.

Should it come up, what are/aren't you okay with as far as illusions and the like? I'm okay with whatever.

Are you okay with him attempting "suggestion" bits or mind control on your character? Yes.

And is it okay/not okay for him to attempt to draw blood and get leverage? Yes.

Are you okay with him attempting possession? And if yes, are you okay with him drawing blood/being able to force it? Yes and yes.

If yes on possessions, what powers/abilities would he have access to? Jeff is a completely normal human, and physically weak, to boot.