I know you are in high school and are unfamiliar with these forums, but please post your questions in the hSDN forum or the pre-allopathic forum. This is a forum for medical students.
You may want to spend some time searching before creating new threads, because your questions have been answered hundreds of times in the pre-allopathic forum.
In general: your major doesn't matter, as long as you do well. I don't know of any 2 year undergraduate programs. Generally it takes 4 years to earn an undergraduate degree. It is possible to graduate in less than 4 years if you take more than full time units, but doing this would give you no advantage in terms of medical school admission prospects.