Also try Johns Hopkins - they had a dwarf (I think he referred to himself as "a little person") go through a few years ago, and then get into a surgical residency.
As for how to do surgery - the table moves. Up....
and down.
MRI - when I've had my two MRIs, no one was in the room with me while the magnet was on. And that would only apply if you wanted to be a radiologist, I believe.
How to get around the ER efficiently - heck, folks with two legs can't do that sometimes. I know a guy in a wheelchair that was taking chemistry lab and aced it. No, he didn't have anyone helping him. He carried his own stuff and poured his own chemicals. He did just fine. Besides - I kind of envy being in a wheelchair when it's time to tube someone. You have a great spot while the rest of us have to kind of hunch down awkwardly. I don't see it as a problem at all unless you let it be one.
OP - go for it. You are really the only one who can judge yourself in this regard. Just be prepared for the questions at interview time and absolutely NAIL your exams and questions!!!