RE: 1
The time stamp records when the note is written to disk (since no other event has more primary significance) but you could write a macro to drop in a slug or anything else in the text box. The text box, that is, is subject to macro expansion.
The point of the slug, though, is to identify subsections of the master file larger than the note itself. When I go through Web sites looking for news items, I may collect half a dozen from one site and three from another, so I would change the slug just twice.
RE: 2
If you visit the Napkin thread, you'll see exactly how to do that in the discussion. And there's even a version with Control + Option + Hyphen to Save a note.
I'm not going to roll that into the current version because Webkit (which is the technology behind the Custom HTML Prompt) requires that Control + Option hotkey combo so it's far too easy to introduce a conflict with a similar Keyboard Maestro macro in someone else's system.
But if you want it, that discussion shows you how to do it. Just make sure you don't have an existing macro with the same trigger.