Here is a picture of my basking set up. As you can see, the water is filled up to the top. I have a very generic basking log attached to the aquarium and the lights set up. My 3 turtles all find a way to squeeze up in there and bask. You don't have to worry about the light being too close to them either. As long as you have a good amount of water that fits the size of your turtle they it should be able to regulate it's body temperature.
With that sad, I forgot to mention that a submersible water heater isn't necessary if you have both UVA and UVB lighting. It's important you have both. One is used for basking and the other substitutes the sun by providing some form of vitamin D. I'm not sure how it works but this is what it's suppose to be xD
Your turtles will need vitamin d to help them maintain calcium levels and promote shell health. For what you've told me about your turtle's diet, she needs a lot more calcium. Yes RES turtles should take more calcium the younger they are but for your case your turtle's growth is stunted. Most RES mature into adults in 2-3 years and that's about 4-5 inches. RES can grow up to 12" long if not longer.. so it would explain the mass shedding. It's trying to grow into it's right size perhaps.
I think it's very essential you get a tool (rock) to help your turtle in shedding it's scutes. Maybe after a really good shedding it's shell will start to look lumicent, hydrated, and not so much dry or flaky.
If you're going to give your turtle fruits make sure it's only about once a month. They don't need that much of it :) Leafy vegetables are good to leave in the tank daily. They aren't difficult to pick up either so they won't ruin the water quality of your tank or anything. Try different vegetables all together. Stay away from ice berg lettuce and gold fish. Most gold fish carry disease. They are also very fatty and they carry a vitamin RES lack the enzyme to break down. Variety of feeder fish is good.
Some foods that are high in calcium are shrimp, krill, worms (most worms! If you can get them live the better), etc. Most pet stores sell a calcium bone type thing specially made for turtles :)
Remember that diet and lighting go hand in hand in promoting and maintaining shell health ^_^