wow, both you guys are wrong.
I did a little (very little) work with the Forumla SAE team up here on E85. From that I learned that yes, you will have to use more fuel (the a/f ratio of E85 is somehwere arround 9:1, unlike the 14.7:1 of gasoline.) The advantage of E85 is that you can run high compresson or high boost without fear of detonation. This will yeald more power than you would be able to get out of your car by using gasoline.
Ethanol shouldn't corode the engine, I've seen lots of manufacturers using E85 with aluminum blocks. I think the main concern is in places like the fuel tank where the ethanol will just be sitting there. The only thing you'll definatly need to change over are the injectors, the fuel tank (need a bigger one, or get a fuel cell and make sure its anadized aluminum or another metal) and new fuel lines, pump, and possibly rail.