Last time I fed them kitchen scraps and leftovers and kept them in a pen so they weren't running and fighting. They particularly enjoyed pizza, French toast, and cooked veggies.
Our friend used to raise meat birds. He lost his homestead in the divorce but still has his processing equipment. He said it's not worth setting up for 6 birds, but if we could buy 10-15 then it would be fine. We helped him once and processed about 45. He built an automatic plucker that can do two birds in about 15 seconds. With all of us helping they were going from cage to ice bath in about four minutes.