With regards to this 32-bit and 64-bit nonsense. It looks like both versions are downloaded to the same 2GB temp file.
Then depending on which system you create the media or run the setup within, that's the version of Windows 8 you'll get.
So now I've nabbed my 64-bit Windows 7 disc back and reinstalled it, I ran the wizard again and re-created the USB drive which has less space free now than it did before so I must have the 64-bit version. Yay! I am happy once again.