Ideally if you are going to breed from your birds you need to have un-related stock obtained from different sources, from time to time I obtain fresh stock to breed from ensuring my birds are free from deformaties and are highly fertile, the best ratio of birds to keep good fertility is 3 females to 1 male, keeping more than one male is possible, only i find if they have been brought up together and then it is best to keep the 3 females to one male rule
You can keep just females for laying unfertile eggs if your intention is not to breed with them.
Never breed from birds with defects, for example crossed beaks or deformed feet.
Males do not mature quite as fast as the females, and it takes a few weeks for the females to settle into laying so I usually wait until the birds are at least 10 weeks of age before saving the eggs for incubation
After the birds have been breeding for some time you will notice that the females may suffer from bald heads this is normal from the male treading them, if you have too many males you may find this more severe in which case you will have to start splitting the birds up to prevent suffering.
Coturnix quail are not good mothers, they may go broody and sit on their own eggs if conditions are right, though this is not a practical way of hatching quail and i would not recommend it.