The best way to mix and match different color birds is to hatch and brood out the various colors together. Putting an oversexed teenager roo with veteran hens is a roo nightmare waiting to happen. Mixing different age coturnix is dicey at best. One may want to buy or build a few more pens for generational development.
As far as brooding goes, Bill has a decent formula. It just gets blasted out of the water here, when I brood down to 78 deg. F. in my basement, then put them outside in 99 deg.F weather. It's a regional thing, but you should keep your chicks at a comfortable temp until they are fully feathered with their adolescent feathers. Then they will molt to adult feathers based on whether it is cold or hot.