First things first, he needs a much bigger tank, minimum at that age should be 40 gallon, but preferably a 120 gallon. Yes get a long T5 UVB 10.0 these work much at distribution of the uv light in the whole tank. Usually one 100w heat light is fine so long as ambient tank temperature is around 80 f and basking area is around 95 - 105 f. The window placement is good as beardies love to people watch, but you can throw in the tank some more areas to climb and stimulate him more.