Him turning white doesn't sound like a problem. It might just be shedding. Usually it's the dark colors you have to worry about. On his most recent "poo" there should be a dark part and a lighter part. What color is the lighter part on yours? He also might be turning white to release heat which...
Lots of chameleons just dont like people or anything else that moves that it cant eat.....over time it might get more established and used to you when it learns your its food source and maybe eventually he will hand feed which is great for bonding.
If you did have a solid sided cage it would need have at least a 12" x 12" screen opening on one of the sides at least 1/3 of the way down (not at the very top) as well as a screen top. This allows hot air to rise and cooler air to rise through the hole allowing adequate ventilation.