Roosters don't care what breed the hens are. I've got a mixed flock, and to my rooster Solomon, a hen is a hen. (Now, he might have some favorites, but that's another story) Most here recommend 10 hens per 1 rooster, but with some roosters (depending on temperament) you can get away with less...
Usually, for pullets, their combs become bright red when they reach sexual maturity. I would assume the same for cockerels. You might just have a faster-maturing cockerel and a slower maturing one.