The XNA is looking fine, although I will not get to look too much further into it for a bit, other than tinkering with it here and there. I forgot to mention that the other requisite component is Visual Studio 2005, or Visual C# 2008 Express Edition
, which is free, and the .NET Framework SDKs.
. If you are teaching at a school, you could look into getting a Dreamspark Account
, which has everything you need (and again, it is free). Failing that, I may be able to help you get a free three-year MSDNAA account, which also has everything you need.
C# is comparable to Java, if that helps any. I guess there are probably plenty of other places on the net to get the nuts and bolts regarding the differences, because I can't be authoritative on that.