I apologize for the lack of updates.
So far I've been unable to restore the system to the point where I can recreate the same errors that I originally reported (even after following my own notes - oops). I've received such a random set of errors, I think there's far more wrong with my backups than previously thought.
For recovery, I've gone the zmlmtpinject route and recovered user mail manually - which worked pretty well.
At this point I'm no longer in need of assistance on this thread.
The major lesson to be taken from the experience, stop when you get an error and post here, maybe someone else has a solution!
Thanks for all your assistance!
Robert