My recommendation is to not rush into buying a long lens. I did, years back, and actually the first two long lenses I had were pretty useless - there's no point getting a big telephoto lens if all the photos end up blurred! The IS is helpful with long lenses, as is using a tripod, but that's something else to buy and carry... Lenses can be very expensive, but I'd try to go for the most expensive that you can afford - or you'll only end up spending more in the long run when you decide to upgrade!
If you want to get some ideas on how to use the camera, other than on automatic, try picking up a photography magazine or two - there are some aimed at all levels of experience. I found them really helpful.