The idea behind the Minimum Common API is to document the minimal collection of Web Platform APIs that ought to be implemented by Web-interoperable runtimes.
By looking at the APIs that are already implemented and supported in common across Node.js, Deno, and Cloudflare Workers. If there were at least two implementations among those -- either already supported or in progress -- then it was added to the list.
Oh heavens no. The initial draft is just an initial draft. A first stab at a collection we need to work through and finalize.
I don't know yet. That's something we still need to work through.