That sounds so much like the work of a dog, they seem to love gnawing on feathers, especially long rooster tails. The Blue Kote will help discourage the other chickens from pecking at his skin and at the emerging new feathers.
I'm sure you'll eventually get all the kinds of chickens you want as you re-build the flock. I don't put a ton of stock in "what people say" about the different breeds. Sure there are tendencies to consider, but individual results can vary greatly. Each chicken's behavior is a combination of nature and nurture. I bet if your son spends time with all your new chicks and gets them accustomed to regarding him as Bringer of Treats he'll soon have a lot of devoted followers.
I'm sure you'll eventually get all the kinds of chickens you want as you re-build the flock. I don't put a ton of stock in "what people say" about the different breeds. Sure there are tendencies to consider, but individual results can vary greatly. Each chicken's behavior is a combination of nature and nurture. I bet if your son spends time with all your new chicks and gets them accustomed to regarding him as Bringer of Treats he'll soon have a lot of devoted followers.