[samokan]

1. if you mean in a university , I think you need a proper student visa for that. Other than that, you can enroll.
2. NO, if you have tourist visa. On student visa, you need a consent from the school. Basically it all depends upon your visa status.
3. Sorry can't help on that. But some big universities have dormitories so you can save on the rental cause its cheaper.
4. Types.jp , JDV International is good place to start.

Goodluck.