Re: Tips for kids class
We let kids in our dojo played shikko tag and shikko dodgeball (same rules as freeze tag or regular dodgeball but the only way you can move is with shikko and forward or backwards rolls). We only play games for the last few minutes of class...and they have to earn it by paying attention and working hard during class.
As far as ages, I think there could be some benefit so separating older and younger kids but at our dojo this is not really an option because there are just a few kids in the class. Keeping all kids under 13 in the same class has been working ok for us.