With the nipping, tell him no and give him a chew toy. For more stubborn puppies, I would try spraying some bitter apple on your hands until he gets the idea. He's probably teething and maybe you could give him a puppy teether?

The walking behind you thing... he's a puppy... that's what puppy kindergarten is for. I recommend obedience classes. Try putting him on a leash and when he runs in front, stop, wait until he comes back and sits beside you then go on. Reward him for doing a good job. When he gets the hang of it with the leash, then practice without it.

This is what the trainer taught us: think of what behavior you would like out of your dog when a guest comes in your door (example: sitting by your feet) and have a friend help you in practicing this behavior. Reward him for being good. Tell him no for jumping and correct the behavior.

Lastly, that baby doesn't need to be muzzled, even if it is for five minutes. Just play with him, rub his belly, or give him something to play with. He sounds like he's just bored! When he does bark inappropriately, hold his muzzle shut a little and say "quiet" or "shush" then reward him for being quiet. Eventually he'll get the idea.

He is a baby and is acting like a typical puppy. What he's doing is not unusual at all and you can't expect them to come into your house fully trained already. Would you expect your own human babies to know how to walk, talk, use the bathroom, etc.? It's the same principle. Puppies are just human babies with fur and four legs. You have to teach the right behaviors in the right way.