Agreed. 32-bit applications will run just fine on a 64-Bit OS, but 64-Bit applications will not run on a 32-Bit OS. Why do you want to make this change?
I'm not sure why you would want to install the 32 Bit version of windows 7, as the 64 Bit version is much better.
Unless there is a way around this, as in being able to choose while doing the installation, if not, you may or may not have to buy a 32 Bit version of Windows 7.
Agreed. 32-bit applications will run just fine on a 64-Bit OS, but 64-Bit applications will not run on a 32-Bit OS. Why do you want to make this change?