Possibly reviewing a fiver year old story is a bit redundant but, it really is a very good story. I like your version of Harry. He is young and possibly a bit immature but not totally clueless as JKR wrote him. Mr. Mann as a character is a jewel. Keep him!
Harry's handling of the MOB was classic!
I also like the potential relationship growing with Hermione. Not over the top but, again, potentially very good.