Youre doing the pond when it gets bigger right? You don't need UV. It's been proven through long-term use, something the people in the recent UV thread didn't consider. So use that bulb as long as you get your proper temps. But when that burns out/breaks or whatever, next time all you need is an indoor floodlight. Those reach perfect temps as long as you increase/decrease the height from the basking spot instead of buying fancy high wattage bulbs. Floods are also safer and cheaper to both buy and operate.
If you plan on keeping a turtle in that tank permanently, just about the only thing that would work would be a stinkpot, and only one stinkpot.
Big ol' honkin' chunks of gravel aren't the best choice, but they dont hurt. You can try sand with pea gravel mixed in. Turtles like to bury themselves sometimes. Don't worry about impaction either. Unless a turtle swallows some SERIOUS rocks, they should be fine if healthy. Reptiles are built to pass just about anything, and they do provided they can function properly.
Depending on the species you choose, you might need more or less land.
Where's your filter?