Are there any major differences between Version 1.0 and 1.2? If so will they affect the accuracy or validity of the run? Or should there be sub categories for Version 1.0 and 1.2?

Version 1.0 is faster because you can skip 2 levels that you have to play on Version 1.2.

The version 1.0 patch is in the guides section of this website. I think you just replace some files and it works