I am no expert myself, but this is what I learned from various websites.
One female quail will produce one egg per day, no matter what. It's very rare that she will want to sit on it, she basically lays the egg and ignores it. You leave it where it is, she will make a new one the following day.
Breeders use incubators. Quails are not good mother material, it seems!
Cuttlebone and crushed oyster shells (or other forms of calcium), dark greens and other vegetables help the hen to mantain the high level of calcium and nutrients needed. Let me tell you, they eat everything and like horses
If the hen doesn't have enough calcium she will still lay the egg, but it will be without shell.