David and Chris, I love the idea of a Q&A section. Here then are my submissions:

What is the difference between a pingbacks/trackbacks and webmentions?
What is the difference between using a child theme for modifications and an additional plugin, such as the one you mentioned in regards to post kinds?
You often mention that various microformats are ‘experimental’, who decides that and how do they stop being so?

Not sure if my questions make sense or offer any value to anybody else, but they are some of the things that have really stuck out to me while listening.