Yes I do multi-table No_Mercy. My standard is 9 and I'm trying to get used to 12 but I've found my game slips a little bit when I play that many. All 6max NLHE. I think it's vital to multi-table at the stakes I play, both for learning and gaining experience, and more volume means more money if you beat the games.
If you understand the rules of the game and you wanna play I would deposit $50 on something on PokerStars. Nothing wrong with reading books, but I would get my feet wet first, splash around a little and if you like it, buy a book like Super System, No Limit Hold'em: Theory and Practice or even Harrington on Hold'em for some tournament strat. If you decide to play and online and want some feedback, post your trouble hands here and I'll gladly help you out.