I still haven't answered all of those, we're learning as we go. But, I did find a few resources that might help you & your kid as you begin your running journey together.
This Runners World article by Jeff Galloway answers the question.. "how far should my kid run?"
Here's one for beginning runners to help you get started... good tips for kids & parents alike.
This article discusses what kids should & shouldn't be doing in various age groups.
Once you've run, here's some stretching for you & your kiddos.