Can I use SQL Server Management Studio 2012 on a 2008 server?
SSMS2012 is backwards compatible:

http://social.msdn.microsoft.com/Forums/en-US/sqltools/thread/0151c2e8-2281-4a78-86b0-20cc1bfd57ac

Edit
Giving out Aaron's link instead of the old one! Thanks Aaron.

microsoft.com/en-us/download/details.aspx?id=35579

As Kenneth mentioned, you could copy the 2008 BOL (Books online) so when you search the help it'll be relevant to 2008 instead of 2012.