Jared, you need a professional trainer, period. If you don't know what you're doing with an e-collar, you can make him worse. Again, you need the advice of a professional before using a muzzle or he will learn to resist it and you could get bit. Quite frankly, although I hate to say it, in all honesty this is not the dog for you. Please take him back to the shelter and tell them what's going on. Hopefully they will work with him before placing him. They need to know he's a biter, and you need a dog without these issues.