This is a rare dual purpose bird. Some data and history can be found here:
I have found them to grow out quite well on 15% protein grower/finisher ration. Protein in excess of 20% creates more waste from the birds. They are slow growing, fast feathering birds that will provide ample and tender meat from 4 - 6 months of age. They are excellent foragers in warmer months. I keep their feed in the coop and they will not eat much of it.
They are very docile birds that can be handled by children. Related cockerels raised together as chicks will get along well.
Care should be taken with the roosters' large combs in cold, northern climates. Insulated coop with good ventilation can help. Also, the open-air concept coops can be of value.
Egg laying numbers can vary among hens. I've had some lay better than others. At minimum, a hen will lay 140 large - jumbo eggs per year.
All in all, a great bird(s) to have in a homestead flock.