By default FCP might show a not rendered screen but if you opt for unlimited RT it will just drop frames like Premiere Pro.No not rendered screen.
Niether Vista 32 bit or XP 32 bit will see a full 8 gigs of RAM or even 4 gigs. It is one of the limits of a 32 bit OS not a limitation of Vista or XP. Even NT had a 64 bit version.
Other than that I agree with your comments.