I'm sorry, but absolutely EVERYTHING he is doing is because somehow it benefits
HIM. He's feeling you out, trying to assess the situation. He's trying to butter you up by being nice. I would be careful about letting him come TOO much, as it is going to stress YOU out. Come to an agreement, and again, get it in writing.
With a coke addict, you will probably have NO idea if he is high or not, you didn't know for 3 years, right?
Like vicki said...KEEP YOUR GUARD UP.