I would purchase the BRS physio during first year, and BRS path during second year for studying usage for your school exams. I'd reccomend purchasing First Aid in December for second year when the new edition comes out, and you can purchase the second edition of Step Up whenever you want to. Don't worry too much about new editions, with the exception of Step Up (whose first edition was riddled with mistakes), having earlier editions of books doesn't matter that much. The USMLE questions are based on a 2-3 yr lag with respect to new medical advances, and the fields of basic sciences usually don't change all that much year to year anyways.