Sorry but you can argue all you like - Vista 32 bit is pointless
No it's not, not everything is compatible with 64bit both hardware and software, remember the real money is made in business and a lot of people still have P4's never mind certain expensive hardware like site laser scanners.
Depends on your hardware, my previous P5N-E will see 3.5Gb but the P5B will only see 2.93Gb in 32bit.
Hardware limitations, not Vistas.
