In most cases (in the US), you cannot get into medical school from high school. you must complete your undergraduate studies (which is college) after high school. Your major does not matter on your...
In the US, in most cases you first get an undergraduate (4-year) degree - either a "Bachelor of Science" or "Bachelor of Arts" - then take the Medical College Admissions Test, then apply to Medical...
Most medical schools allow you to donate your body to science, but you would need to contact them directly in order to get the propper forms. You would also need to notify your next of kin, to that...