2. You can find the information in "System" under "General" tab; whereas in 64-bit system, it is specified in system information; in 32-bit, it is not displayed.
Note: if you've bought a box version, you might notice there are two installers on the disc, one X64 and the other X86. Please install X86 on 32-bit OS, and X64 on 32-bit OS. If the version you bought is 4.0 or later, it includes only one installer, which automatically installs X86 on 32-bit OS, and X64 on 32-bit OS.