For the succubus, there's a area in town right where the arrow is in this image. You need to move on to that square, then the game will tell you "blah blah this is a secret wall blah" and then you can go to the succubus tower. You can access the graveyard after you access the succubus tower by asking Rinny to follow you and going to the graveyard. As for Fawn's quest line, you can access it by taking her membership card and waiting for her to show near the torture rack a few times.