We all have "stuff" in our past that causes issues in our present. Maybe it would do Hulky good to just tell you and get it out so he isn't trying to bury it anymore? I admire you for being okay with not knowing and for letting him have his secrets, but a little confession goes a long way in healing past wounds. And you may be able to help him deal with it, and let it go.
As for Chip............ he doesn't sound like much a friend -- and if he's leaving your place in such a state of drunkenness how is he getting home? Is he driving? He's going to kill someone.