Congratulations! It's an awesome feeling to open that big, fat envelope.

I'm completely with you on the driving...I can't drive on expressways because semi trucks scare me beyond what words can express. Definitely practice during the summer; you'll probably find that you become more confident. If by the end of the summer you're still not comfortable, then you can find other solutions. At my school, most people do not have cars. The campus is large, but definitely walk-able. Your college probably has solutions for people who don't drive. If you need your car, and only expressway driving scares you, can you have one of your parents drive your car to campus while the other drives another car? It might be convenient to have the space of two cars anyway; you'll be amazed at how much stuff you'll take with you.
The best advice I have for all college students (including myself, but I find it
so hard to follow) is to develop a studying routine. The material taught in college courses is not too much more difficult than what you learned in high school, but college is still hard. College is hard because most classes don't have homework, and you only have around 3 exams (or a few papers) each semester. It sounds like a dream come true, and it is...until it actually is time to take one of those exams and you realize that you have to learn a month's worth of material in one night. And when the whole cramming thing doesn't go as well as you were hoping it would, it sucks having the miserable grade you got on that exam contribute so much to your overall average.
So...study often and regularly. (I'm a hypocrite. I have an organic chem test on Tues. (!!!panic!!!) and I'm spending my time on PC instead of the last 50 pgs of reactions that I need to learn.)
I'm sure that you'll do well. Though it is awful that you have had to live with MI for so long, coming to college already dx'd can be a blessing. You know the warning signs for depression and mania, and you'll already be connected w/ MH professionals who can help you navigate your way through them. A kid experiencing his first serious depression may be so thrown off by it that he fails a few classes or even has to drop out. You'll catch that depression early, have your meds adjusted, struggle, and hopefully make it through without as many dents. My therapist also told me that she has written letters to professors for many of her patients, explaining how an acute episode of the student's illness impacted his/her academic performance. She said that many professors are actually very accepting.
Do you know what you are going to major in?