yes
Yes.
Programs written for 32-bit operating systems will run perfectly well on a 64-bit system.
Only Windows 64-bit operating systems can run 64-bit applications
Yes, except for Windows XP 64-bit and Windows Server 2003 64-bit with Itanium processors.
64 or 32 although the 64 will be able to run 32 bit programs.
no
You don't have to "do" anything. All general-purpose 64-bit operating systems will run 32-bit applications as well out of the box.
Actually, they both make what are known as x86-64 processors, which are processors that can run both 32-bit and 64-bit programs. Check the specifications of the processor for something like "64-bit" or "64-bit Ready" to make sure you can run both x86 (32-bit) or x64 (64-bit) programs!
No.
In simple terms, 32-bit operating systems can only be able to run on 32-bit CPUs and 32-bit apps, but a 64-bit operating system can be able to run both 32-bit and 64-bit CPUs and apps.
Yes.
64 BIT