If you change the cage vertically, it may stress your cham, which is not good for him when he is in this condition. I would make sure that he is feeling better before changing the cage. Though I would get rid of the wood chips...
From the size, I would think it is 4 months, because mine is 5 months old, and she is slightly larger... Of course, each chameleon grows at a different rate...
I've never had my chameleon run away, but here is an idea
Maybe you can leave a see-through cricket keeper on the floor or near the window sill and check once in a while to see if you find your cham is trying to get to the bugs. Your chameleon should be hungry if it hasn't had any crickets for a...
The "black" used to be purple, but it got darker a few weeks ago. I don't have any good pictures, but normally it looks like dark purple... She got mad at me for taking the pics. Also, I have her in a screen cage.