Actually, checking my code, when the CB activation happens (which is either when the user activates manually, or if you've turned activation off in CB then this happens automatically right after registration) my plugin sets the Anjel user data (in an Anjel table) to confirmed - so my gut feeling is that this'll apply directly to Anjel and that Anjel won't sent email to unconfirmed people.
I'm not sure if Anjel continues to send mail if you close the browser window - although I've heard discussions about this before.
Re. is Anjel still in development - it *is*, but the dev. has been very busy and there's been very little activity on Anjel. We actually run a heavily modified version of 0.6.0 where we've applied a number of fixes and additions of our own.
Re. data import & export - Anjel does have this functionality, it's not perfect - it just imports/exports a list of names and email addresses (and some other general settings) but not a list of which newsletters they're subscribed to, but it can be useful nonetheless. It probably wouldn't be too involved to hack the import/export functions to take account of a users subscriptions.
Lastly, there is a feature in Anjel where you can attach content items to a newsletter by selecting them from a list, and another feature where you can attach files to the outgoing emails.
HTH and thanks for your comments!