Actually, I think its okay to put each question in a different thread.
It is possible to have a cage so large that the chameleon has trouble finding food, and it may be harder for you to find the chameleon. So long as you make sure it finds food and water, I guess bigger is better. i prefer to use three stages of cages: Small for itty bitty babies; 1'wx1'dx2'h for young ones around 3-6 months of age; and then 2'x2'x4' or bigger 5-9 months onwards