Living with roommates can be VERY difficult. In fact, I think it is harder than anything you'll be doing at school. I suggest you buy your own food, but be prepared for the girls you are living with to help themselves to it.
The bigger concerns are life style incompatabilities. If you are very studious, you will likely end up with someone who is a partier, and when you want to study, they will want to have friends in your room. I suggest you get used to studying in the library. Also, the neat person/sloppy person is a very common problem. Try having girls agree to a small fine if they leave a mess for someone else to clean up, which can be saved up throughout the year and spent on dinner for you all. Having friends sleep over (including boyfriends) is sometimes problematic, so I would address this before it comes up.
Ideally, you should try to work out the ground rules for these things before they become problems, and then you will have to learn to pick your battles. Good luck.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?