How old do cockatoo cichlids have to be to breed?

I've got a bunch of cockatoo cichlids (2 males and 2 females) that are each about one inch long right now. My question is, how long until they're big enough to breed? Also, do you think they will be able to protect the fry from the rest of my fish (rosy barbs, gouramis, Leporinus, a cat fish, a pleco., and currently two angels)? If not will a .5-1gal. hang on refugium be sufficient? Oh, and do they pair off or do they just choose fish to breed with? Oh yah, and is there any special food or anything you should give them to get them in breeding condition? Any advice helps!