Haha, how diligent! Nice work on finding them all!
You're half right about the second vine scene. It both has a Lewd requirement and also you had to have tested out the Allure Potion at least once. Either with the slime or with Philia. Second slime scene is indeed based on the Lewd skill.
As for the scenes with Mina's friends, they won't have repeatable alternative scenes like the creatures do. More so you'll use their night time locations to access new scenes as I add them/they're unlocked. Just as a little teaser, the next version will have Philia's second scene. Alo'Eth on the other hand won't get any scenes until a particular potion with a particular effect is added to the game. You're right that you'll get the hints for that in the first wing!