From your description, I'd guess that you have a dog on your hands who has previously been allowed to do whatever he wanted, whenever he wanted. He's never been taught that he has to respect humans. That's the first thing he needs to learn! I'd put him on an immediate Nothing In Life is Free program. He works for everything--food, attention, walks ect.

Personally, I don't mind a dog that growls at me. I'd much rather have a dog that warns me than one that just bites. If he had wanted to, when you were trying to force him to sit, he could have put you in the hospital. It's a great sign that he didn't do anything more than growl.

If you are truly afraid of him, he may be better off in a different foster home. I'm not saying that to be rude in any way. I gave up one of my fosters because I didn't trust Summit. I didn't trust her, she scared me and because of that, I couldnt' work with her and give her what she needed. Summit had issues similar to what you've described. I gave her up after she tried to kill my Kayleigh. Summit is now happily in her forever home.