So far, all the HTML that a given page will need is part of the same document. The templates for the dynamic content are all stored inside a hidden div.

I expect that eventually this will cause too much of an up-front load time, so I'm planning on having the JS load bundles of it on demand. Reducing total HTTP requests is a big usability win, in my experience.

To answer your URL question, I use attributes, like this:

http://urbantastic.com/org.html?id=org-8srmt85mtf8t

Which the server ignores, but the Javascript parses and uses to figure out where it is.