ROTC cadets do not have to go through Basic.
They have to complete four courses their first two years (unless something's changed since 98). THose four courses, if you've gone through Basic, are a piece of cake. You may find it beneficial to take the first two years of classes. First, they give you greater familiarity with the ROTC program. Second, they can give you an edge to getting a ROTC scholarship. Third, they're easy As, which is always good for the GPA. Fourth, they're fun and a good way to meet people in college with similar interests.
I had three years active and about three years Guard and I went through the first two years of ROTC for those reasons (sans the scholarship, because I had no interest in becoming an Army officer, wanted AF).
So, no, you're not required and Basic counts as a waiver, so to speak, for the first two years. You will have to complete a leadership school one summer (between junior and senior year). You're paid for it, paid well actually, and it determines if you get a commission. Not a big deal, if you ask me, because I saw some folks that passed it and they didn't impress me.
Take the courses, meet folks, have fun, get easy As.