Another theory of Quirrelmort (which Psy-Kosh came up with) is that Quirrelmort identifies with Harry because he transferred part of himself to Harry when he gave him the scar, so now his ambition is for Harry to become a Dark Lord. In other words, Voldemort split into Quirrell and Harry, and now the one part is trying to make sure that the other part carries out his plan.
This theory is compatible with the wizard v. muggle war theory, if the plan is for Harry to become a Dark Lord and lead the wizards against the muggles.
Hm... I suppose that might actually address the issues.
But wait, this doesn't explain why Quirrelmort would wait 2 decades for Harry to finish the job of taking over the world rather than do it himself, and then groom Harry without any distractions. I mean, Quirrelmort still seems to be quite competent, and we see ever less of zombie-mode. (Besides, isn't leadership all about delegation?)
ETA: There is now a third thread, so send new comments there.
Since the first thread has exceeded 500 comments, it seems time for a new one, with Eliezer's just-posted Chapter 33 & 34 to kick things off.
From previous post: