Need help understanding settings - rotational play etc?

@mightysprite answered most of your questions so I'm going to answer number 4. As far as I know, the settings are saves-based. Meaning the settings you set for one save, will not transfer over to another save, unless you save as/copy the original save (if that makes sense). Apart from graphics and audio settings, I'm not sure if you can make 'blanket settings' (for lack of a better phrase) from the main menu.

Also, hi and welcome to the game and forums.