Chocolate Island Ghost house: Pass the first room, with the Lakitu wannabe dangling the fire, then, in the second room, there are Boos that turn into stone when you look at them. Lure them to where you see a door out of reach above you. Turn them to stone, hop up to the door, and you've beaten the Ghost House!
Blue Switch: Forest of Illusion Water Level. Play through almost the whole level, but, just before the home stretch with all the Rip-van-fish, the Charge'n Chuck, and the end goal, go LEFT. There is a fake wall right next to the Yellow block. Key's behind that wall. There ya go!
Hope this helps!
