Perfect vision is not essential. Surgeons can wear glasses in the OR, and in surgical specialties where you use assistive devices to see what you're doing like surgical loupes or microscopes, I'm sure those devices can be adjusted to whatever degree of correction you need. As far as feeling faint when you see blood, that's something you get used to. It's not uncommon for med students to pass out and hit the floor (better that than falling into the surgical field!) their first time in the OR. Many of those still end up becoming surgeons, OB-gyns etc. It's all a matter of desensitization, as well as taking simple precautions like going into the OR well fed and well hydrated, not locking your knees when you stand, etc.
Physical endurance does play a big role. You stand in one place and hold sometimes uncomfortable positions for hours at a time. This is particularly true in orthopedic surgery, where trainees (medical students and residents) often have to stand there holding heavy limbs while the attending operates, sometimes for hours.
Don't feel like you have to have this question figured out before deciding if you want to study medicine. If you end up going to medical school and deciding you enjoy the OR environment and do well in it, then great! If you go to medical school and discover that you don't, you can always bite the bullet and suffer through the total of 3-4 months of surgical specialties you are required to do in med school, then go into a field where you never have to see the inside of an OR again. I was one of those people who went into medical school thinking "surgery or bust," then discovered that I just wasn't cut out for it. I'm starting residency in an non-surgical field of medicine in a few weeks, and I regret nothing.
