The character scenes all list their requirements, so if there isn't anything above Metatron 10 affection, there's no hidden 12 aff.
Badon is the end of the plot, will be extended in the next update soon.
Gallery will be revamped in the future back into the game proper since it was only ever meant as a way to see the choices you missed in the opening, every other lewd scene is repeatable already.
Hope you've been enjoying it, the next update is.... somewhere around 2-5 work days away!