Thanks for your reply! I think the finance side of it worries me most, because there's no way I could afford international student tuition fees and everything in America. I can imagine them saying "sure, you can do it. But you have to pay everything yourself, and none of the credits will count towards your degree." In which case I'd probably have to *facepalm* a few times and abandon the idea. Darrrn.
But I have no idea how to even go about this... when would be a good time to ask, if I wanted to go in between my second and third year of study?