I don't like the idea of using any one feeder as a staple, but horn-worms make a great feeder as part of a balanced diet. They are high in calcium, high in moisture, low in fat, but low in protein.
The number you feed depends a lot on their size and the age/size of your chameleon. They grow...
Nice pics. What are his length and weight?
I really like my panther, but I would like to get a bigger species one day, maybe an Oustalet's is a good option.
I think that is fine, a little yellow near the end where it connects to the poop is okay. Check this out for more info https://www.chameleonforums.com/poop-101-a-120171/. Also, it's called a urate and comes out solid because they don't have a bladder like we do.
They are high in calcium and moisture and low in fat. The main drawback is low protein. However, they make a great addition to a balanced diet. My cham likes them whenever I can grab some for him.