The Weasley Homestead

I'm trying to figure out what screen-writer Steven Kloves and director David Yates have against the Weasley homestead, commonly known as "The Burrow".

First, in a completely invented scene in the film version of The Half-Blood Prince, they have Bellatrix and her pals burn the place down. If that's not bad enough, in the movie Harry Potter and the Deathly Hallows, Part 1, they have several characters (like Mad-Eye Moody) call the place "The Burrows", plural.

In an interesting contradiction, some characters call it by its singular name and others by its new plural name, both in the film and in the special features that come with the Blu-Ray version of the movie.

Strange. J.K. refers to it, consistently and without exception, as "The Burrow" across all six books in which it is mentioned (I don't find any mention of the Weasley home, at least not be name, in The Philosopher's Stone). Why change it in the film?

Oh, which reminds me, from what I understand, the first novel in the series is called Harry Potter and the Philosopher's Stone in just about every English-speaking country in the world except the United States: so why do the British producers refer to it constantly as Harry Potter and the Sorcerer's Stone (the American title) in the Blu-Ray extras?

By the way, I recently picked up the French version of the first novel and I think the direct translation of the French title is Harry Potter at the School for Magic. Neat.