At 10 years of age, he is old enough to take care of a camera.
If he wants to experiment, encourage him.
Regarding the "little stage", that sounds like he wants a "light box" kit.
You can find a complete set-up with lights, diffusion box, and tripod for around $50 or less.
Here are some examples:
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Delectronics&field-keywords=photographic+light+box&x=14&y=18
Regarding the camera:
We need to know how much you are willing to spend for the camera.
My son is nearly 10 years old and begging for his own camera. He enjoys doing stop motion animation and I'd like to get him a point and shoot that would be good for this application. I also plan on helping set up a little stage area with diffused light and tripod. I am on somewhat of a budget.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic