I'm not a senior but I can answer some questions. No they don't need a light. You use a undertank heater thats all they really need. The light is usually a low watt red or blue so you can view your gecko without hurting their eyes. Bright lights actually hurt their eyes. Since they are nocturnal. You can get all the calcium and D3 through suppliments. They don't need a large amount of D3. but they do need some.
Right now I only dust calcium don't have and undertank heater.. But I do have a exc terra heat mat.. How is it?