They may grow larger in time, but meat gets tough the older the bird gets. So I would butcher at 7 or 8 weeks give or take a few.
You can play around with whether or not two males with harems will work. However if you have a weaker male, he will be subject to aggression.
I always mix and...
Are you raising these birds for meat only?
If so, what I would do in this case is butcher all birds by 7 to 8 weeks of age. They won't be as hormonal and breeding, so there should be less fighting going on. Keep these young birds slated for the table in their own section of this cage/pen. I...