There is an aquatic plant list here:
http://redearslider.com/plants.htmlI've thought about using sand in my stock tank, I will probably try it over the summer. Rubbermaid stock tanks are black/dark grey so it's hard to see the bottom. The sand will make it easier to see inside. A heater is totally fine, Ebo jagers are very reliable. Some filters can hold or attach heaters to them, so that's an option.
The lighting situation depends on your setup. You only need one light per basking area.
*edit - sand comment*