Nice summation. Some of the deficiencies you mention have been brought to Adobes attention. What they do with it is a complete mystery. Maybe those bugs/deficiencies will be ironed out with the release of CS6, somewhere in 2013, when a 64 bit version can hopefully be expected, or maybe not. Adobe is so closemouthed, that nobody really has any idea where they are moving when and why.
Found the work around but why is there an issue with using a USB mic for VO. USB is not new.
This is most likely an ASIO driver issue. If you have not found ASIO4ALL (sounds like either you have, or that you have found similar that works), it handles most ASIO driver issues. This is more a function of the drivers supplied with the USB mics, and is not Adobe-specific, nor is it PrPro-specific. Many higher-end programs fight these same issues. From Audition to ProTools, some USB mics, just will not function out of the box.
Knock a few clips down to DV when capturing, and report back if the same issues exist. I work only with DV on a similar system, and the damn thing is fast as hell.
Your issue with playback on an external monitor overriding playback in the reference monitor happened to me with the 4.1.0 update. I confirmed this when Media Encoder stuffed up on me and I had to re-install everything. Versions 4.0.0 and 4.0.1 worked OK but 4.1.0 has the issue.