No you don't have to separate them. I have had plenty hens set on eggs in the coop and hatch babies. The only thing is the babies have to be able to get to the food and water. The hen will protect them from the other chickens. A coop is usually not an ideal place due to the set up.
If you're talking about separating by breed, then yes since a rooster will cover a hen regardless of breed do if you're interested in keeping a pure line then you will have to isolate your flock by breed. Otherwise, if you're just interested in chick, the sexes should be housed together.
Like the others appear to be, I'm not sure exactly what you are asking. One rooster can usually keep about 10 hens fertile if that is your question. It does not need to be one rooster with only one hen and they do not need to be the same breed.