Thanks for the thorough answers, Alexander!
The answer to #3 is a disappointment. In this case I'm using the WordPress REST JSON API:
and it inserts a "parent" field at multiple levels in the JSON. So it sounds like Kendo cannot be used to create apps for this particular REST API.
Is there a hook that would allow the JSON to be pre-processed to remove/rename any "parent" keys before the observable is created?