i use wacom, and i would recommend getting a medium. the large are normally too big and not necessary for a student and the small is too small. the medium should work just fine.
I'm not very concerned with it. Its really all about convenience. do you want it quick and ready or do you want to spend the time. images are mainly to help emphasize a point. if a stock photo can do so, then it does the job, so go with it.