I'm new to this myself, but if it makes you feel better, I have the same cage and same questions/problems. You are not alone

While I can't answer your questions with certainty as I am new to chameleons myself, I can tell you I did use bamboo throughout my cage. I bought a fairly thick 6' pole from my local nursery for $1.99 and cut it into 3 2' strips that all fit perfect across the cage, all at different levels. As the bamboo is hollow in the middle, I gently tapped a nut into the hole in the center of the bamboo and bolted it through the screen from the outside. As I bolted it on, I slipped Cable Clamps (
http://www.homedepot.com/p/Gardner-...ps-12-Pack-PPC-1550UVB/100175900#.UjutHj_8LTc) through the bolts so that I can run vines throughout the cage.
I'm still not completely finished and I had 2 ends that I could not fit a nut into, so I simply passed a bolt through the screen to support the bamboo. The bamboo rods are bolted on the one end and are not moving at all.
I had also purchased the egg crate drop ceiling diffuser (before reading this thread), but I was planning on attaching it to the back of the cage to prevent water from getting all over my wall when I mist and maybe help keep some humidity in the cage. I chose it because it was already 4' x 2' and was fairly light weight. I assumed because it was meant for lights it would be somewhat heat resistant--not that it will be near my basking lamp, I just figured it would not discolor from the lights. I just received some neodymium magnets in the mail today which I was going to use to attach it to the cage. Figured that would make it easier to take on and off if needed and so it wouldn't be permanent. I will say it's very fragile and cracks easily.
I bought a plant stand, but I like your idea much better (flipped pot) and it is much cheaper. My wife doesn't feel the plant stand is strong enough anyway. Currently have a smaller Pothos and a 2' Schefflera that I also needed to raise up.
I broke the first rule of buying a new reptile...I didn't have the cage setup before I got the animal. Chip was an impulse buy at a Reptile Expo a few weeks back and we're still tweaking the setup. We have some major cage remodeling planned for this weekend. Maybe he'll stop giving us the stink eye when we're done.
Lastly, in complete agreement on the Reptibreeze...not as sturdy as I thought it would be. My door started sagging after only a few days but I'm scared to adjust it because every other screw I took out and put back in ended up stripping the aluminum frame (I had to because they mislabeled the pieces in the factory and I had to figure it all out as I was going along). I have to "lift" the door every time I open it.