I came to this site because I was searching how to harvest my very first chicken...or in this case rooster. I thought I would post my thought here since you were wondering about a rooster playing nice with children and defending the flock. I started out with 5 hens and a rooster but not by choice, the rooster (a black Australorp) was supposed to be a hen. I decided I did not want any roosters because my wife has a small scar under her eye from a run in with a rooster during her childhood. According to her, they always go after your eyes. I did not take the time to verify this because for me the chance of one of my young children losing an eye was not even worth the time researching it as I mainly wanted laying hens. But, alas my hen ended up being a rooster. My kids were fine with the rooster at first, but he has chased them and gotten all puffed up at them as if he was posturing. While he did not actually "attack" them, the fear they now have about going in our backyard to play supersedes any desire I have in keeping him. Hence why I am here to learn the best way to harvest him.
Oh and as far as protecting the flock; I am down to 2 hens. The other 3 were eaten by either a fox or a weasel. He is big, beautiful and loud...but thats about it, so as far as a real need for a rooster: It is my opinion that unless you want fertilized eggs, there is no real advantage to having a rooster around. I do enjoy their "attitude", size, and colors, so I may get another one someday for that purpose.
I should note; black australorp is the only rooster I have personally owned. He is fine around me and does not posture, but all the women in my home, he goes after. It almost makes me think of the alpha male pack leader characteristics in dog packs. I do not know enough about chickens to comment on that though, just my observations. I have been around a few silkies and they seemed calm to me. So if you are determined to get a rooster, I would research the breeds to see what might be best. I would think maybe a smaller rooster would also be less intimidating to young children, as this australorp I have is one of the biggest chickens I have ever seen.