On the steering wheel based on your step by step it seems the new steering wheel will have the extra plug for the right side MFSW controls, not the car? I'll pull the air bag when I get a chance and confirm.
I pulled the 9W7 and confirmed it is part number 7P6 035 730 C (Sw version 0440) - a Google search seems to confirm that is the correct part for 9W7. So a good start.
As the MFA+ from the NAV equipped units have a compass and display song titles(i think), caller id and phone book - How do I determine which combination of these features will work with the RCD 510 (not NAV) and for the features that don't work, do they just show blank or throw errors. Eg the compass? Or the phone book - is the NAV holding that or the 9W7?
I'll have a part number from a Canadian 2011 NAV instrument cluster I can share soon.
Good point on the MDI - it would be great if it could have both an iPod interface and USB at the same time, but that doesn't seem likely.
I have been looking at the Gentex mirror, just not sure I like the adaptor plate and they don't seem to sell a VW specific model. Maybe the dealer can remove the old mount from the windshield?