I'm not a dog trainer at all.
However.. When it does not involve my own dog i do have some insight on some things because I have worked at an animal hospital and i currently work at a humane society so i see lots of dog types and personalities.
But it sounds like you guys need to work together with a professional dog trainer. One that specializes in aggresion.
You are doing the right thing to work with him and not wanting to give up on his life. Which is awesome! I believe 99% of dogs can be rehabed even if its not "perfection". Any dog can have the ability to bite, just some have a much bigger threshhold than others.
To me it sounds like he mainly is being destructive in the house? Perhaps he does not see you as pack leader and therefore has no respect for you. And so for the growling when your near his food its because its HIS food not your food that you gave to him. Stuff like this a professional trainer can give you adivice on. And i cannot see his behavior so i really do not know, but the trainer can see his behavior and help you from there.
Anyways, i truely advice you to do some research to find a trainer, it may cost a lot of money and time. But it will be worth having a professional dog trainer help you guys on your relationship and build from there.
My advice though.. If you cant control him and he drags you around I wouldnt bring him to dog parks or anywhere if he gets loose and he can do harm to others, just for now until you have control. And if anything. it would be for him, so he doesnt do something that will lead him in a direction either of you want him to be in.
I wish you both the best of luck!!