That has not been proven to date, particularly because Uberpie does not take the time to correct AI errors and the consistency is worse now than even when Uberpie couldn't keep on character when hand-drawn.
They should not have different save files - but this is an instance where they do. In the past any Taffy Tales with the same Major.Minor.Patch (i.e. v0.89.8) but different -bugfix (i.e. v0.89.8a vs. v0.89.8c) could share the same save files on Windows, Mac, and Linus machines (Android could not). It was when Major.Minor.Patch were different that saves couldn't migrate - hence why most times there was a preloaded save for players to start at new content.
However, v0.89.8c seems to break saves from any other v0.89.8. since there is no new content in v0.89.8c - it is best advised for people who have already played through another v0.89.8 (a or b) to not bother to install c unless they wish to play through the update again.
Yes. It's only in the first half of v1.07.3 as a separate route. You could literally just download v1.07.3 and use the save/cheat code on the preloaded save and view gallery of the scenes to see if it's something you would actually enjoy. OR you could preview my speedrun video of the netorare content here:
#29,199 Some netorare fans enjoyed some did not.