Need site architecture help

I am considering moving the Coyotos site (www.coyotos.org) to Drupal in order to let a larger audience participate in building the site. Some of my questions are entirely mundane, and I would appreciate pointers to existing solutions. Also, in one place I could really use some help trying to figure out how to apply the Drupal structuring tools to our needs.

We have a large body of existing email archive from the EROS days. I would like to import this as discussion threads so that we can start an editing process. Is there an existing mbox->forum importer?

Similarly, we have an existing website, and I would like to move those pages into Drupal. Is there an existing set of procedures to import these?

We sometimes need to do large (i.e. offline) edits. Is there an easy way to do this?

Portions of our site are under version control and *must* remain so. Some will continue to be updated entirely outside of Drupal. I would like a way to build "wrapper" pages for these so that these documents can be viewed by Drupal visitors and comments can be added to a comment section. Is there a way to do this?

I see the "book" and "article" concepts in the documentation. I also see that they are slowly unifying. Is there some place that gives a simple theory of operation for when and how Books are intended to be used?

Most of what we need here Drupal supports already.. One thing we definitely want that MoinMoin does not support is an approval process for new users. In general, our goals are:

• Anyone can browse (easy)

• Only registered users can comment (looks straightforward)

• Existing users can create their own pages, but must first request the necessary
  privilege (so that space doesn't get eaten alive).

• Only "developers" can edit certain content.

• Developers are associated with projects, and should only be able to add/edit
  pages in those projects.

All of this should be capturable with roles, but I am unclear how to structure this.within the Drupal mechanisms. Help and pointers would be greatly appreciated.