1) Check out the BBB courses
http://www.psych.upenn.edu/bbb/BBBCourseOfferings08c.htm
They are mostly neuroscience based and very interesting courses. Often they aren't difficult to get through and the profs are quite interesting. Courses in particular that I thought were good to take were Chemistry of the Brain, Clinical Research in Emergency Medicine, Biological Basis of Psychiatric Disorders and Clinical Psychopharmacology.
2) You should check out the RWJ website for more details or the Penn website but I think you need at least all 9s on the MCAT and you have to have a 3.6 BCPM. But double check that against the websites. You also have to be nominated by your advisors so if you are interested, approach them to see if you are eligible and find out if they will nominate you.
3) Other advice would include to work hard and take advantage of the research opps you will have with so many great hospitals in the area. Be very careful with what your advisors tell you since the ones that are now there are not very qualified and the director is leaving. Consider hiring a private advisor if you can afford it, or confirm what you are told with your peers or via experienced people on SDN. Do very well in your classes and apply early.
I wish you the best of luck. Philadelphia is a great city - enjoy what it has to offer