About your explanation of Micropub: it's not that it enables you to create Notes, it's that it enables you to use other services to post on your own site. This post, for example, I write in Aaronpk's Quill. Thanks to Micropub, Quill can actually post this reply to my site. But Micropub can be used to create whatever post on my site, as long as the client (Quill) and server (my site) both support that kind of post. See it as an open posting API :)

Oh, and I believe step 3 should be WebSub, which is just PubSub. I'm not at step 3 though.

Anyway, welcome to the Indieweb!