I agree with your Burrow views to a degree. However, I do think the chat about Draco and the cabinet did help solidify what is going in the story, which I think is needed for viewers that haven't read the book. The fight was pointless and not that satisfying, but I think the reason why the director wanted to include the fight was to show that the death eaters are on the move and attacking people.
As to Snape, the actor that plays Snape has never read the books; he feels the films should be separate from the books. It's clear in this film he has never read the books, and I thought this was his worse performance as Snape. He has been really good up to this movie. My main complaint, like you, is that he lacks the bite that the Snape in the books posses. He has been one of my favourite Harry Potter actors up to this film.
The actor that plays Dumbledore really surprised me this film. It actually felt like the calm, controlled Dumbledore from the books, which is the Dumbledore I like and I think needs to fill the position of headmaster. The previous films it felt like he was a teen girl on an emotional roller coaster. I should note, the first actor that played Dumdledore is still my favourite, and the new Dumbledore is another actor that hasn't read the books.