The Genius bar might do it for you (you'll just have to ask), but installing RAM is so easy, after you watched them do it you would almost certainly feel like you wasted your time not doing it yourself. Check out Apple's support articles and you'll see how simple it is.
As for backing up, it's always a good idea to back up your computer, but I've never bothered to do a backup specifically because I was installing new RAM. If there's a problem with the new chips, you can always remove them and everything will (or at least, should) work the same as before.