I have to agree that Michigan has one of the best business schools around (although there are plenty of others that are very good). One word of caution is that Michigan's undegraduate business program is a two-year program: junior and senior. You apply to be admitted during your sophomore year, and the competition is very tough - the internal and external applications are considered in the same "pool" and when I was a student there (*not* in the B-School but had several friends who were) unless you had at least a 3.7 GPA, you might as well not even apply.
And yes, Ron Warhurst will work you hard but you will not run in every indoor meet. Also, if you already have a long-term plan spelled out with your current coach, you better decide who you are going to listen to. If you attend college you'll be expected to listen to your college coach. As we saw last year "cooperative coaching" doesn't usually work out and with all the publicity the Webb situation brought I can't imagine any DI coaching willing to try it. You're either with the program or you're not. Given your strong feelings about mileage and wanting to redshirt, maybe the best idea is for you to attend a college close to your current coach and continue to be coached by him/her, and not join a college team.