Finally a subject I DO know something about. Canines: wolfs or dogs!
Muzzles certainly have their uses and their place, but for the problem you are having.... well.... this isn't the place or time to be using a muzzle. Pits are as sweet as any other animal when born, its when humans make the wrong choices that they are taught aggressiveness and poor social behaviour. I wouldn't want you to lose your friend because he becomes aggressive with a muzzle on. His behaviour is telling you something!
The problem with him destroying items by chewing is his way of telling you he is fearful and needs some boundaries. Buy a STURDY crate, but you cannot just dump him in there when you leave and expect all to be well when you come back. He has awesome jaw muscles and will take most crates apart like so much fodder. It will have to be metal, a good gauge.
While you and your roommate are in the home with him, let him explore the crate, like a great gift you have for him, be excited. Then place him inside with a blankie, and some of his toys, close the door and wait 15 minutes. He may scream and fret, but dont let him out until your time expectation is up. Do it several times during the time you are home. Each time give him a treat, lots of hugs etc for having been a good boy in his crate. At night, he should be sleeping in a crate.
Crate training a canine is a way to provide a safe haven for him/her to go to when all is hectic about the home. From the first night with a new puppy, crate training should be on your mind. He will know where his "room" is, and it can be used as a time out spot, a quiet refuse from a busy home, and a secure place to lay his head and rest.
Furthermore, I would suggest a $110 investment into a puppy class. I don't usually recommend a specific place, but will tell you that PetSmart has an awesome training program for novices. It isn't so much about training the canine, but more about training the people how to deal with the canines and how to teach boundaries and get the expected results.
Good Luck!