I say wait on the AppleCare til the near the end of your first year. It's the same price, they may screw up on your ending date (I bought my rev. a 12" in January of 2003 and renewed my AppleCare in October of 2003 and somehow I'm covered until October of 2005 - I got an extra 9 months out of it) and you may decide to get a different computer or something.
As for what else you need, I've been able to get by with my external keyboard/mouse combo with a monitor. That won't work in your RV, though. You don't really need a riser or anything. Just make sure you don't slouch. If I'm working at a coffee table, I'm fine with kinks in the back. I only get those when I'm sitting on the couch.
Oh, and with today's recent announcement of the Airport Express, you've gotta get one of those. Just 'cause they're cool and you asked
