I can't see how they'd be allowed to not let you know though. :\ They have to realize that you may or may not be able to make a certain important decision until you hear back from them. If you're really that concerned about not hearing back, maybe you could try contacting them and asking about it?
Grad school you mean? Graduate school is something you can go to after you finish your undergraduate studies. It allows to you get a masters degree rather than just getting the bachelor's degree. It varies based on what you're studying, but grad school is usually like 2 years long. And you have less classes.
Yes, it is very nice.