It's lonely when noone responds to your thread, I know.
There are many using the forum that know much more than I, but they are probably busy, so I'll give you what I know about combining chickens.
You can put chickens together after a "get-acquainted" time of several days, where they are separated only by wire and they can't get too aggressive with each other. This is especially true of older chickens, but I suspect the same should be done with younger babies. After they've gotten acquainted thru wire, let them be together. You'll see them establish their pecking order and it won't be friendly, but hopefully, won't do anything too hurtful.
You'll likely have more roosters than will get along, so anticipate having to place them with someone else. If you have small bantam hens, a big rooster could hurt them, so pick your rooster according to the size of your hens.
Have fun with your new babies. They'll be cute, and you'll have fun trying to figure out who is what breed! Good luck. Pat