Just a thought here,
Bryce was very very quiet when we first got him. Then as he got a couple of weeks older, he was very growly (it could've seemed like agressiveness, but I could tell it was something else), barky, sassy I might say, and hyper. We wondered what we did to that wonderful perfect Newfie boy.
It was our fault. He was not getting as much excersize as he needed, and he needed new training challenges. So, he was frustrated. He wanted to do something, wanted to work, wanted something, and we were not giving it. Once we figured that out, we gave him an extra little walk (as young as he was we did three to four miniature walks with lots of stimulation; new things) and began some new training things like legnthened his training and began stays and did it sitting, laying, standing, etc. And we did push ups! Sit, Laydown, Sit, Laydown. It took care of the agressiveness that wasn't really aggressiveness. We actually had a training and walking schedual worked out, everyday at pretty close to the same time. This was more for us than Bryce.
When he started barking, we would tell him no bark "Shhhhh" and put our hand on his muzzle letting him know we didn't want him just running about barking. We also did small time outs too because bored or not, little signs of being pushy is a no-no. So he was never taken out right when he acted that way. He got a short time out instead. Once he calmed then we'd play and go on about our daily routine. He learned polite and calm=fun and play. Growly pushy=time out with door closed in ones face.
All in All, He was flat out bored and trying to let us know! He needed stimulated. And yes, it took a long time to get things together. We did the routine daily and he's just 7 months and we are still doing the routine, but, he's very very calm and mellow now! For the most part! As for the biting and pulling. We have had our share! I still don't own a pair of pants without holes in them from sharp puppy teeth. My sweatshirts are the same. He's not as bad now. But I think all puppies do this type of thing.
Robin