CoffeeCow:
I'm seeing a lot of great advice on here for you. I can speak of the saddles or aprons only to make a joke of what I first thought when I saw them for chickens, along with diapers. I can't keep myself from thinking of that Miller Light commercial where the guys deliver to the dog show and are astounded to see how people treat their prized pooches. That said, I do understand the utility of having them now. If your cockerel is being that rough on one, then it might just be a great idea for you.
You seem to have the right idea toward cockerel behavior, though. My RIR cockerel is 5 months old, and would be a little rougher if I didn't keep him in line in combination with the one adult rooster I have. Having Vic, the adult mixed breed in my avatar, I think has saved me a lot of work with Roo and the girls. I am a firm believer that most behavior issues aren't genetic, per se. They are a product of their nature, and as such can be worked with, if you have the time and patience. As a male myself, I can attest to the many stupid things I did when I was going through puberty. There are boundaries that must be set, and if not done at this growing stage, will result in a lifetime of heartache. Yes change is possible, but the odds go down the older they get, with all animals. Puberty is when we figure out who we are, and set most of our personality. A firm hand that gives your cockerel his space but also enforces boundaries will go a long way. As he matures, he will be there to raise future generations with the same firmness as you instilled in him.
My cockerel will bite me if I try to pet him like I do the girls. I don't see this as bad behavior, just him setting his own boundary. He doesn't want to be touched, and will bite harder if I persist. Occasionally he will come and let me pet him, and loves to eat out of my hand like the adult rooster. Keep in mind, he's just a chicken. I take care of them, and someday they will take care of me, whether eggs or on the table. If he resorts to an all out attack on me or anyone else, I guess we all know what happens. He's just a chicken on my dinner table. If its just aggression, I want to know why. They are very proud and dominant, so if he's just setting a boundary that doesn't affect me, then ok. Otherwise, back him down and I set the boundary.
Good luck