Geeze you're eager!
You can't breed similar families of fish because they will cross breed. Hybrids are no good.
The other thing is, what would you do with heaps of baby fish? When it comes to killies, there isn't a huge market for them in NZ.
As for a breeding group, I guess as much as your tank will safely accomidate. But in realitly, (an exaggerated example) what would be the point of say 25 females to two males, producing at least 50 eggs a day, 350 eggs a week, 350 fry to feed in a couple of weeks, minus deaths from pollution etc, you would have around 250 fish to try and re-home.