These are really good questions.
I've published Yoga for all Kids in ebook and softcover. It is a series of 15 moving poses that are adapted for kids. My background was as a classical ballet dancer, then teacher of rhythmic movement before falling into yoga at age 30. There are no poses that put pressure on the spine, no shoulder stand, no head stand. That is absolutely correct not to begin adult poses till age 12 when cartilage has hardened. Just like a ballet dancer shouldn't use toe shoes till age 12. Here is my article about the book at BellaOnline:
Yoga for all Kids