5. Save file: For Windows users, the save is written into the Windows Registry. There is no separate save file. If you receive anything from anyone to edit your Windows Registry, you do so at your own risk of bricking your computer or introducing security issues.
If you find your saves disappearing, someone recommends this: Save the game and exit through the Main Menu, do not simply save and close the game - doing so risks your saves.
For v0.95.7 (Season 5) - The game starts at new content automatically. No need for a preloaded save.
For v0.89.8 and before - There is a save code listed in OP (see #2 above) to start at new content for v0.89.8 and unlocks all previous gallery content. When you start the game, select load game and click on the included save in slot 1-1 and enter the save code and cheat code, as well as name Mary, Tiffany, and the MC whatever you want.
Saves from previous minor versions are incompatible. Saves for v0.89.8a and v0.89.8b are compatible for v0.89.8c, just install the new update and they should be in the menu. Same with saves for v0.95.7a, v0.95.7b and v0.95.7c being compatible with each other.