There are many breeds suitable for children. One option that is often overlooked is to get a group of bantams. The eggs are small, but perfectly edible, in fact, sort of "child sized", if you know what I mean. Silkies are bantams and I think they are perfectly hardy if you give them proper housing, and that is a bit easier because they are smaller and more sedentary than the large fowl laying breeds. I have an outdoor coop with silkies and cochin bantams that is about 4x6 and has had 10 or so chickens in there for many years. It's not of ideal construction, but still I have never lost a bird due to bad weather and we've had some ferocious winter storms here in that time. I use a cheap tarp on the windward side during the winter to keep out most of the snow. Moving it close to a building with electricity to power a heated dog water bowl has been a huge help. Sometimes they go several days without attention in the winter. Summer is actually harder, you need to ensure they don't run out of water.
Other breeds of bantams I highly recommend:
Cochins (love these, like silkies, but some in prettier colors)
Ameraucanas (little blue eggs and sweet little hens)
D'Uccles (Mille Fleur is a popular color, very pretty little things)
Polish (everyone loves a little mop-top chicken)
The cool thing about bantams is you can fit a whole group into a pen barely large enough for a pair of the larger breeds, so you could build a "bantam" condo with several pens and keep different breeds in each pen. Their small stature makes them kid-friendy, even a mean roo is not a threat if you just stand up and laugh at him. I have a mean lavender Ameraucana roo that tries his best to attack my hand at times. I let him do it, it tickles. I have one mean LF rooster that has drawn blood on several occasions and I go in to that pen always on high alert, but the bantam just amuses me.
So, you should consider bantams for the kids, but if you want lots of eggs, or want to sell them, then you need a pen of large fowl. If you want a pen of purebreds with a roo, I recommend Orpingtons or Welsummers. They seem very mellow. If you aren't keeping a roo, then Cream Legbars are perfect for a laying flock with small children, they are calm and small, but excellent layers, and their blue eggs are eye catching. Most of my Legbar roos have perfect manners, but I've had a few with a "Napoleon complex" that liked to challenge me. They are quite intimidating for their size, it could terrify a child to have them jump up at them. They are immediately cut from the breeding pen, because I'm selecting for nice males, but I don't recommend then for a "first rooster" because of the few bad apples I've had.
we are only allowed 6 hens which is fine we are a family of 4. I will definitely be doing my research and checking everything. Are there any issues I should be aware of with housing different breeds together? Or is that a big no no?
