I have the 32-bit version of 12.04 LTS. If I upgrade my machine to 12.10, does it automatically turn into a 64-bit OS? Thanks!
No. Not unless you use a 12.10 64bit disc, which will probably eradicate the 32bit install.
The online update system replaces packages with the same architecture, as some 32bit machines won't be able to run the 64bit binaries. Even if it were able to, and automatically detected this, there is some minor packaging differences between the two, and you probably see a lot of 32bit packages being installed for compatibility with some applications (like skype, for example).