I wasn't sure about the crabbe/goyle thing. Just said I thought it was, and maybe he looked diff because he aged (they all look WAY different in this movie) or maybe a new actor playing whichever one it was that 'wasn't them.
Also, I didn't say Harry's dad CAST the Patronus, I said he WAS the patronus. The silver stag was Harry's fathers Animagus form. As for the quidditch match, There were two. One where Harry fainted because of real dementors, and one where Draco and them pretend to be dementors, and HArry casts the patronus at them, scaring the crap out of them
And as for Hagrids hut, I said I didn't know.

They just up and changed it because they changed shooting locations. Maybe that was the sole reason they changed the location of the Willow, because they didn't have the same locale to shoot in.