how do i backup my ps3 and game saves before i change the hard drive and how do i change the hard drive etc

to save the game saves put in a memory stick, go to 'Game' > 'Saved Data Utiltiy' > Then press Triangle on your saves and 'Copy' them to your memory stick

to change the hard drive:

http://www.youtube.com/watch?v=BkM9wiZePfs

yeah a usb drive will be just fine and its really easy just insert it and press backup utility