A: The sharing of a single profile between 32-bit and 64-bit clients isn't recommended nor is it supported. This is because of the differences in the way both the OS and the applications save settings and data.
Ideally you would use a single platform for clients. Or you would use a third-party solution such as AppSense, which separates the user application settings from the normal profile and can handle cross architectures and different OS versions.
Microsoft has a good document at "Windows User State Virtualization," which walks through how to decide upon the right user virtualization solution.
We do more than Windows--check out all of John Savill's FAQs!