RES really aren't too difficult to care for. That is a pretty good sized tank, but it wouldn't hurt to go bigger eventually, especially if you get females. Males normally get around 7-8" and females can get up to 12".
The filtration and heater sound good. I use a Stealth with my turtles as well as they are next to impossible for turtles to break.
As far as lighting, you'll need both a heat lamp and a bulb to provide full spectrum lighting including UVA and UVB. There are some bulbs like mercury vapor bulbs that do both, but they are expensive. For a heat lamp, I use a regular outdoor spot lamp from Wal-Mart. Pretty much any powerful bulb works for this as long as it keeps the basking spot around 95 F. For the UV bulb, there are several different brands of flourescent bulbs made specifically for reptiles, so go with one of those. Also, make sure that there is no glass between the UV bulb and the turtles as glass filters UV radiation.
Diet isn't difficult either. The bulk of the diet should be made up of good quality water turtle pellets and then supplimented with things like dark leafty greens, and occasional foods like krill, feeder insects and worms, chunks of fish fillets, or even some live feeder fish (I tend to feed minnows and avoid goldfish as feeders as they aren't very nutritious)
Edit: Well, it looks like while I was typing this, Coura snuck in and gave you a link to ATP. That's a great site for turtle info.