From your desciption it sounds like you need more utility than pure speed. If utiliy is your thing than a nice hybid like the Trek FX series will get you a good amount of gear range and the ability to add a rack and fenders to you can carry your books and not end up with road grit up your back. I've been using the Axiom Appalachian Bag (saddle bags) that I bought for under $30 that I've been using on my daily commute for 1.5 years. Cheap, and with a little extra water protection spray they have stayed dry on the inside even with some terrential rain. I see lots of folks who don't like the way tripples shift, but both my hybrid and my road bikes are triples, and have zero problems with shifting. I almost always ride in the front middle gear, but on some steep hills I sure am happy to have that granny gear available. The taller gears I generally don't get to use much unless I go down a big hill, but I live in a pretty flat area so not many hills to go up or down.
For bike fit you are probably beyond the size of most Womens models. Do try to see if any of them fit, but if not try a few different bikes. There is not right or wrong when it comes to bikes and fitting your body. Some just are going to work better for you than others. My sister is 6' 3 and she ended up with a Raleigh Passage series. She tried some Gary Fisher bikes as well, but the Raleigh fit her best. My bother in-law and I are 6'4" and 6'2.3" respectively and we both found the Gary Fishers to fit us better. Its like trying on shoes, you just have to put them on and try to see how it feels.
Happy riding,
André