As far as lighting, I agree with Cobra. Which I interpret as "you don't need a bright light and you especially don't need a light that put out or adds heat to the viv.

One of my FBT's was very dark when I got it, and I noticed back when I was experimenting with different types/sources of water that alkalinity seemed to make the biggest difference. If I used spring water or distilled water then he'd green up. If I used tap water, then he'd get dark again. The tap was had sat for several days to dechlorinate itself. However, I knew that our tap water was definitely on the alkaline side as many municipal water supplies are around my area. The spring water I purchased was slightly acidic and the distilled water is neutral ph. So I always attributed the dark color to the ph of the water, though I've never seen anything about it from a knowledgeable source.

But if you've got hot bulbs or lots of uv shining down on them and nowhere for them to escape from it, that's just as good an assumption as the ph.