Here is some more.
Cake: medium cave, southwestern side standing by an octopus. You need 2 items, "mustard" and "sauce." Both can be found in the southern end of medium village near the item shop (check the rock in front of the shop and the boxes on either side iirc). Take your items to the medium cave. Use the mustard on the octopus (it steals 500g, not 100% sure this step is necessary, but worked for me) then the sauce for a tentacle scene.
(After, the octopus disappears and Cake says she's hungry for takoyaki, implying there's more to do. There's an octopus-related item you can unlock in the medium village shop I suspect is the key. It needs 10 octopus ink and 8 honey. Ink drops from the octopi, but I haven't gotten honey to drop from anything).
Edit: The level 2 bees in the fire forest (4th area) drop honey, however the item unlocked from the shop in Medium village is "Big Candy" and has no effect on Cake, who's still says she's hungry and "it buys octopus in village of the medium" or some shit. She's similarly uninterested in "rock bread" so not sure what else she wants.
That said, making the big candy seemed to be the trigger for Choco's second scene. Speak to her after you buy a big candy (and pay, if I'm not mistaken) and she'll bang you right in front of everyone in the inn.
Cotton: maid in castle. After her peeping scene, buy a white potion from the castle shop and a sake from the first village. Head to the tower and find a knight asking for strong medicine. Give him the white potion and he'll indicate that Cotton is fond of sake. Back at the castle, give her a sake and she'll say she's dtf but you must wait (talking to her again will just say she's drunk). Leave and re-enter the castle and speak with her again to trigger the scene