The dog we had before Topher had a
serious barking problem...oh my goodness could this dog bark! Plus it was a sharp, loud bark that hurt the ears.
Well, we did some research and found that by yelling at her to stop (as we were doing) was, to her, like we were barking right along with her...lol...little did we know! We found that what worked for
us was first, to teach her how to "speak" or bark on command. Once she mastered that, she was able to learn "quiet" on command. It took time and
lots of treats, but she finally did do it. It's a
long process...especially learning to be quiet for extended periods. You just have to be
consistent with the training and it will work. Being
consistent with any type of training is the most important part.
It is a problem, though, when you have people in the house who aren't going to be helpful with the training. It's like taking two steps forward and one step back, for the dog, when you have people around who are going to do all the wrong things when the dog barks.
Can you sit your roommates down "sit!" lol and discuss it with them? Perhaps train them how to do the same things you are doing (whatever techniques you choose to use...mytrixie's ideas were good, too!) After all, I'm sure everyone in the house will benefit from having a quieter dog!
Oh, as far as the nipping goes, I've found that Topher (now 8 months), is really growing out of that stage. We sternly say 'no' and with hold play whenever he nips, but he hasn't done it for a while now. Perhaps it's a phase they go through as puppies (?) I don't know.
Good luck! You might want to look into an obedience class, too. It's a great way for us doggie parents to learn how to do the right things.