The calming influence of the shirt is not surprising. There is some science behind it that was the inspiration for the Thundershirt, which helps many dogs who suffer anxiety and fear of things like storms, fireworks, or traveling.
First, maintain calm and control around your pup. If you get excited or anxious, he will feed off of that and become more bitey.
When he bites, use keywords and phrases, "No bite." Say it firmly, but not angrily. Fold your arms over your chest so that he can't access your hands to bite. Try replacing your hands with a toy for him to grab.
If he doesn't respond appropriately to these measures, get up and walk away. Ignore him. This will help teach him that he won't get attention when he does this --- and puppies crave attention.
Establish a daily schedule/routine of activities. This has a calming effect. Start obedience and trick training. Focus his attention on positive things. Training sessions should be brief -- just a few minutes a few times a day.
Read up on teaching bite inhibition:
http://www.yorkietalk.com/forums/gen...nhibition.html
Puppies can be a handful, but with patience and consistent effort, things will fall into place.