1. On the finacial aid tip, the max that is allowed for loans is 38,500/year (subject to yearly review by congress but, it should not be a problem) dependent upon your school's cost/budget. You can contact each school and ask what there projected budget is. Of the 38,500 8500 is elidgeable in Subsidized and the rest will be Unsubsidized.
No school will offer you an offical finacial aid package until all acceptances are final ie after May 15. This may answer your fin aid questions.
2. Do not worry about money, unless there are tens of thousands of difference, go where you feel the most comfortable. That will be more benefical than having 20k less in loans in the end. So if there are any that you can absolutely rule out, you should let the school know asap, as you obviously have.
3. About Pitt, the only thing I would have to say do not eliminate a school that still has potential untill you visit. Personally, I almost canceled a visit to a school that I had had as #10 on a list of 9 but, after my visit it jump into the top 3 and I really contemplated matriculating there.
4. I too was woried about not completing the classes that I had included on my AMCAS app. Schools usually do not care if you complete all of the classes unless, as previously stated, they are prerequisites or preclude you from completing a degree that you have indicated you will obtain. Do not sweat the extras.
Hopefully I have said something worth value to someone.
Best wishes,
Richard