I was suprised and disappointed in them for not helping the Cullens. Laurent was about to kill Bella for Victoria; the wolves had no choice but to destroy him. If it was the other way around I know that the Cullens would have helped. I guess they came through in the end though (well most of them).
Maybe Tanya was Jealous of Bella because Edward turned her down and picked Bella. She might not have wanted to risk her family for Bella. Its obvious in Breaking Dawn that Tanya doesn't like Bella at the wedding.
It was wrong. Just because Irina had a problem with the wolves, doesn't mean the Denali's should have left them hanging like that. Even if it meant that the others would have to leave Irina behind for a short time.