Can I give one piece of advice from a seasoned college veteran? DON'T go home for the first month. Stay at school, in the dorms and GET INVOLVED! All the freshman that you will be living with are facing the same new experience that you are, and trust me, this is when a lot of close friendships are made. When you go home, you miss out on a lot (ouch...lesson learned the hard way!).
Seriously, you probably will get homesick at some point. I didn't think I would either, but it's a weird feeling. You miss your life at home, where your "comfort zone" was, and part of you wants to go back to that...but at the same time, you are so excited about this new adventure and you don't want to leave. And trust me, being away from home for 2-3 weeks really isn't a comparison. With those trips, you know you are going to be home within a matter of days, and while the missions trips are full of work, it isn't quite the same as college and being on your own. Chances are you will probably experience homesickness at some point - especially when you actually GET SICK! You may not...but don't be surprised if you do.
Just remember to stay involved, be active, and ENJOY this time. When you graduate, it's full force into the working world, and trust me, it isn't the same!