I will answer everything in order:
- How much do personality mods affect the robot?
- The Personality Module only affects what Jun said during Sex or Small Talk Interaction, and nothing else.
- How far into the game do personality mods start to appear?
- Every Module on BigDaddyHurt's Shop is randomized. It all depends on your luck whether it will appear in the shop or not.
- The game has multiple endings, and none of them were good. Is that changed now, or are we still stuck with all bad endings?
- There's no Good Ending, there are only Bad Endings. The only Good Ending is "You've finished the whole game without encountering any Bad Ending".