3. We already have a lot of content with hagrid, snape, minerva and helena. For the other teachers there isn't much (flitwick for exampl, pun intended as he's short) but that's not a problem. And the content with the prefects is almost more than the teachers (if you count old plot). The only students that marcus interact mostly are ginny, colin, draco and parvati; there isn't even that much content for them as there is for other characters.