For the love potion scene you just gotta have a love potion when you click the option to buy his company for the night. The group sex scene is available right after the bandit camp events and the ratkin scene is a variant within the same scene. You need a love potion for both of these scenes to happen. I dunno how far you are in the game cause these scenes are immediately available just from either having the potion or in the other case just progressing the story a bit =o