light the candles that he holds with the fire ability. next, follow him until you get to the room where he sits down. when he sits on the candel, vacuum him up! Do NOT under any surcumstances let him...
Find all of Mario's lost items and show them all to her. Once she's told you the information behind all of them, she'll willingly show her heart without harming you so that you can "put her to rest".
I'm not completely sure but you could try beating the shroob's and get magic window and then give use snack basket. note if it doesn't work then don't complain because I haven't beat him.