How do I know which version I downloaded before all of these updates? Says there's a windows and a windows 32 bit? I just recall purchasing and downloading it. Would it affect the save file somehow?
For the version, you can find it in the main menu, in the lower left corner.
As for the 64 or 32bits, they share the same folder for the save file, so don't worry about it (if you really do worry, enable the cloud save)
Also, the 32b version works on 64b systems, but not the other way around. a 32b version cannot run the 64b version.
If your PC has more than 4GB of RAM, it's a 64b.