With children that young, I highly recommend not getting a rooster. There is a real possibility that some of your chicks might be roosters. If you got them at a feed store, people pick up chicks, and then accidentally put them down in a different brooder. And with some breeds, sexing is not 100%. It is helpful to plan ahead what to do with a rooster. Roosters can often become aggressive, and they almost ALWAYS attack children first, and young children's faces are not that far from the ground. Little children wild running, jerky movements, and even their falling down, can cause a rooster to attack.
You have years to enjoy this hobby, and it is better to start out smaller, and work into it. Figure out what works with predators, with the climate, with the neighbors a little at a time. Beware of being bitten by chicken math, as overcrowding does lead to horrible behaviors that can really take the fun out of having chickens. Measure your set up, find the area of the coop and divide by 4, find the area of the run and divide by 10. That gives you a starting point for how many birds will be fairly comfortable when confined. Even if you plan to free range, you need to be able to confine them if needed. And the long dark days of winter will confine your birds to the coop when they roost at night, nearly 14 hours at a time.
With children this young, I would suggest, letting them hold the chicks until they can't catch them, which will be pretty soon. Then I would just let them watch the birds through the fence, and gather the eggs. They are pretty young to be holding and petting older birds.
Mrs K