I built a bumpout on the back of my coop that is divided in two for new babies every spring. This last spring I had 3 groups of little ones so the youngest ones stayed in the garage brooder for a couple more weeks until the oldest chicks were ready to join the big girls in the main coop. The bumpout brooder is open on the inside to the main coop but has chicken wire on it so the big gals get used to seeing the younger ones until they are old enough to join them.
At first I just let them out into the run with the big girls (both areas have their own pop door) and I monitor them the first couple of times. The big girls do try to push their weight around but soon learn that I won't tolerate it much. I also have areas for the younger ones to hide from the big gals in the run area. There is no way to avoid the pecking order adjustment completely but this helps keep it less traumatic.
I thought it would be hard to do the final move to the big coop but found that, as time went by, more and more of the younger birds were just following the big gals into the big coop at night and fighting for a spot on the upper roost! They integrated all by themselves! My outside brooder is empty now so I cut out one panel of wire so all the birds can use this area to walk around in until next spring when I get more babies and I close it up to start all over.
This kind of setup works well and I think you'll find that you will be adding birds more often than you thought. When I first started I thought that I'd have the same birds 'til they stopped laying but stuff happens. Predators, you've already realized, can change your plans quickly but so can disease, group dynamics and sometimes you get some problem birds that just need to go (feather pickers, egg eaters, non layers...). I haven't had most of these issues but just predator problems are enough to realize that new birds every year or two are a part of life with chickens.
Good luck whatever you decide!
