not yet, but I'm not sure why it would be a problem? WebMentions just sends a URL to where the other is being mentioned, it's up to the reciever to expect a resource with http://schema.org metadata.
Totally! But check out what we've done with Webmention and Microformats for the last few years: https://2019.indieweb.org/summit#indie-rsvps All these RSVPs are via Webmention Microformats. Click thru the permalinks to see the original posts!