If you provide shade and cool water, the chicks will be fine. You can begin acclimating them to the warm temps by cutting off any air conditioning to the room where you've been brooding them. Do that for two or three days, and then move them out.
You will see some stiff competition between the two age groups since they're close in age and size and they're all immature. Since the run is blessedly huge, get creative and break up the space. Make it so there are places for smaller birds to run behind and evade pursuers. Install those perches and stumps I described. I even have a swing in my run that the younger birds love to hop onto where the older ones won't reach them. Get a flock scratch block and you will have an additional interesting feature that can help decrease the focus on the newcomers.
The more interesting you can make your run, the more likely you will see a peaceful flock.
You will see some stiff competition between the two age groups since they're close in age and size and they're all immature. Since the run is blessedly huge, get creative and break up the space. Make it so there are places for smaller birds to run behind and evade pursuers. Install those perches and stumps I described. I even have a swing in my run that the younger birds love to hop onto where the older ones won't reach them. Get a flock scratch block and you will have an additional interesting feature that can help decrease the focus on the newcomers.
The more interesting you can make your run, the more likely you will see a peaceful flock.