To be honest you are putting the cart before the horse so to speak. I would not worry about residency and what that will be like until you are in medical school. Things may change by the time you are done with residency and hours may be less than 80/week who is to say. I take it one step at a time, first get into medical school, then finish medical school, then worry about hours working as a resident. I do know that the 80 hours is max hours allowed per week, I am not sure but maybe some residencies will have less but not by much.