Here's a website that shows people essentially having them on the roof blowing outward/upward essentially like Beman said to pull the stagnant air out of the enclosure, which in effect would pull in fresh air from below through the screen.
Yea the white LEDs could be used to help brighten up the cage a bit. It'll provide your Cham some more light in those darker areas towards the bottom. (Oh yeah! Grats on your cage btw!)