That question all over the map. Let me try and spell out basics around physical storage.

Drives letter are logical drives. It represents blocks of space that windows identifies are drive...

Thanks Manu for pointing out some essential material!

It looks like that section on special clustering considerations you cited only applies to the 64-bit systems, which is a relief for me,...

I think you should also consider using AzMan. Let the windows users and groups define the user population, and the AzMan data store can persist the provisioning data completely outside...