I had a small enclosure for the housing. Lone star chameleons has a YouTube video showing his setup. I just copied it. They poop ALOT. So I kept a tray on the bottom.
Yes they should be dusted with calcium.
I would also pluck off their big spiky legs so they wouldn’t cause any complications with digestion. Also be ready to expect bigger than normal bowl movements.
15-20 crickets is a lot. How old is your chameleon?