((((zen))))

I'm sorry you're dealing with cat fights and such. I can relate.. I live in a dorm, and in a suite with three other girls. My floor is all gossip, all the time. The girls talk about me a lot, and even though it really gets to me, I try not to let them see it. I smile and I'm very polite [even though I really feel crummy]. I think the best thing to do is just be friendly and sweet, because it will really get to them. Even if you don't feel like being friendly and sweet, it will get to them because they'll know they're not getting the best of you, even if you feel like they are.
As far as the gossiping... You can either remove yourself from the situation, or be authoritative. You can say something like, "Guys, come on now, we've really got to get to work on this project." For me, it would be very difficult to say that because I get kind of scared.. but if you can, great . If it doesn't work, I'd suggest bringing the issue up with someone who has authority.

Hope this helps