Bit of both tbh - piperchapstick, you'd be surprised about how many actors don't read the original versions of the adaptations they're starring in, either because 'they want to concentrate on scriptwriters vision and not add different interpretations' or because they just can't be bothered! I'm always surprised, for example, that hardly any of the GOT cast have actually read all the books.
So, while she may have thought it was a stupid question, there's still no reason to show it. Same with the other question, when they asked if she was like the character she played - yeah it's not exactly award-winning journalism but it's a fairly innocuous question. But again she went for a sarcastic 'No I fucking hate her.'
While I think it's refreshing to show a bit of personality, there's a difference between a little bit of sarcasm and just being rude. Like the interviewer said, she's paid a lot to be in these films, and promoting it is a key part of that. It probably isn't any actors' favourite part of their job but you can be polite for 5 minutes ffs! People do a lot more for a lot less.
On the other hand, getting her name wrong was ridiculous, that's journalism 101, and the way they continued slating her after the interview finished was incredibly unprofessional.