Nice attempt but there are quite a few spelling mistakes in here that you might want to fix up: Parvati Patil, Padma Patil, Godric Gryffindor, Gilderoy Lockhart, Kreacher and Regulus Black... :)
Gave up halfway through because without hints it's impossible to guess which characters you included in the miscellaneous section. Actually, without hints it's impossible to guess most of it--there were loads of names that you didn't include. Angelina Johnson, Thorfinn Rowle, Igor Karkaroff, Ernie Macmillan, Madam Rosmerta, Arabella Figg.... I could keep going forever. Otherwise, not bad.
Good, but add more for slytherin, hufflepuff, and ravenclaw. Also you should delete boggart and dementors because those are like one in a million and there are tons of other creatures mentioned but besides that, very good quiz!