It's completely normal behaviour for his age but I know exactly how you feel. It can seem that they're being really aggressive and you worry you might have a problem dog but it's actually all just part of the process. The most important thing to do is to teach him that mouths don't go anywhere on skin. What I did with mine was if he started nibbling on my fingers, I would say 'no' very firmly and loudly and push him away (I really wouldn't tap him on his nose either, by the way). If he ever put pressure on, I would say 'no' very loud and firmly again and then get up and leave the room for a few minutes. They do get the message but it's a learning curve and they need time for adjustment and you also have to factor in that their brains are developing in a certain way and at a certain speed so they're not going to get it immediately. You just need to create a routine and stick to it. In terms of the barking and growling at you, I think he's telling you he wants you to play with him. Again, I would say that routine is everything here and that he needs to learn that playtime is on your terms, and not his. Again, what I did with mine when I noticed this demanding attitude, was put him out the room if he got to be a pain. We had (and still have) about four play sessions a day where I bring out his toys, he picks one and then we play for about half an hour or an hour depending on how I feel. Of course they always want to play but looking back, I can see now that when they're at this very young age, they don't know that they're annoying you or worrying you with their temperament - you're very much an object to them: the source of all their food and pleasure and play and what have you and because they haven't learned to have 'manners' yet, they just behave, well, like any typical toddler really. In terms of the pee pads - I think what happens with puppies is they see the pad or paper and then they have their wee. It's not that they're trying to miss: as far as they're concerned, they 'saw' it which means in their puppy mind, they're 'on' it. I would think you just need to kind of keep repositioning him or put down a few more pads to make the area bigger for a little while.
But honestly, please don't worry. He sounds like a great little fella to me and everything he's doing is normal. It might seem that he's changing his behaviour from week to week and that's something to worry about but truly, it's completely normal - their little brains are changing and learning at an incredible speed and because it seems so sudden, you think 'uh oh, problem' but really, give it a few months and you'll see he'll settle down. This age: between 3 months and six months is when I had the most 'issues' with my puppy but it was a great learning experience for both of us and the next yorkie I get, I'll know exactly how to deal with as a result. Create routine and sort of try and see him very much as you would a young child who needs to learn and you can't go wrong, really
