I had a similar problem in first year. I had a snoring roommate who always happened to get to sleep before me. I'd recommend buying some earplugs, they don't block out all the noise, but they do help. I also like reading before bed as I find it makes me tired. Try to figure out when your roommate is going to go to sleep and read for 15-30 minutes before then.
I'm not sure if you're a morning person or not, but I'd try to schedule your classes so you have as few 8:30 and 9:30 classes as possible. I figure sleeping in an extra hour or two is better than just not having an hour or two of sleep and, in general, the mornings aren't too noisy. Ideally, you could even coordinate your schedule with your roommate so that she doesn't wake you up when she has morning classes.
As far as roommate agreements go, it really depends on your roommate. My roommates (I had a triple) and I kind of took the agreement as a joke and didn't really give it much thought, but everyone's different so I can't guarantee that this will be the case.
Apart from snoring, I found that the room above our room was loud (I never figured out what they were doing, but it sounded like they were jumping on the floor with the intention of making noise
). I rarely, if ever had to deal with parties keeping me up. Then again I lived in Moulton, which is considered to be a quiet res.
Hope it all works our for you!