Hulo there! Sorry I haven't been around much lately, I'm catching up with family and friends I haven't seen in half a year. Won't be online much till next week or so but I'll give you a very brief outline now. 

What happened the first day (which is all we've done so far) is a little scandal at the start, then the students had breakfast and either went to classes or were recruited for a mission. We've just finished the mission. You don't need to read the whole IC as most of the characters there will be gone by now... What you should read is the first and last IC post. 

Where you could jump in, is in saying your character is headed for classes or that they're part of the group that's assigned/asked by the principle to give Hazumi a music lesson. They won't know her personally yet so it's pretty convenient. :) Or your chara could just come to the school because they've recently found their Fragment (refer to the ooc if you don't know what I mean).  

We don't need any specific type. We try to have complex characters overall so I couldn't say we "need" anything in specific. Perhaps just students that can play musical instruments, but that's not a necessity. However I do suggest you make a student and not a freelance or teacher.