Ah, yeah, I was answering 1.

Access to disk is... not great, I agree, but I'm not terribly worried about it. My plan is to eliminate the checked out file tree and plug the version control straight into the core data structure of the editor. I just hash the nodes of the underlying concrete syntax tree, which is my Emacs-y homoiconic data structure.

The downside is that the ecosystem for this product starts out empty. It's a whole new set of protocols, data structures, and APIs. Even so, the JS ecosystem does contain quite a lot of code that I think will be of value