I saw a great idea once by someone who posted photos of his free range. Essentially, what this person did was get one of those metal shelves from Target, Walmart, etc., (like these:
http://www.abtec.com/nexel/00724A.jpg) and only left the bottom and the top shelf (putting the top shelf as high as it would go). Then, they took a shower curtain and attached it to the back three sides, leaving the front wide open.
You can put the lights on top of the top shelf, some plants on the bottom one, and set up a misting system or dripper there that keeps the water confined to that "wet area." The cham can still leave that area if you put more trees and plants beyond the confines of the shelves, but that way he was a specific shower/water area he can go to when he's thirsty. And if you have a misting system set up to run at specific times, he'll learn when it comes on and run towards it. Mine do, at least, but they're in cages.
All you need are buckets or something under the bottom shelf to catch the water and you're good to go. This is what I would do if I could free range inside.
This didn't answer your questions specifically, but I just wanted to mention this idea in case you liked it

The cup feeding can be tricky sometimes with chams. Hopefully someone else can help you out with that.