When I was a kid, this is what my Dad did for a living. He bought wrecked cars from an auction in Denver (now owned by Copart), bought parts, had them fixed, and sold them. Back then the numbers were basically, $3k for the car, 3k to fix, and 3k profit. Then it all changed, the manufactures started cancelling the warranty, and so prices cratered. There's still a market, but but make sure you research it.
He suggests targeting new cars that have not had model updates for as long as possible. So there are used parts available. Otherwise airbags alone will kill the deal. Many times it is best to buy a car hit in the front and one hit in the back/different location and combine them.
No idea of the profit per hour. It will depend on your proficiency swapping parts, scratch and paint... And the "last 10 things". Plus don't forget detailing.