Absolutely NO on the car.
Absolutely NO on staying at your place, even one night. Especially if your not going to be there!
Absolutely NO on helping him with his mess. It sounds like he has earned everything he has.
I see a retired Lawyer looking to take advantage of, most likely, another unsuspecting helpful person. I suspect he has done this before, probably why he had a falling out with the pastor. A con man with legal knowledge and a week in your house without you being there will have you coming home to nothing, and you will never get the house back (or you wouldn't want it if you could get it back). I hope it works out for you.