Absolutely spot on. I don't think he should have been sent off, but he did give the ref a decision to make, and the ref only sees it once, from one angle, at full speed. There have been many, many worse decisions made.
Again, spot on. I thought it was a terrible game until the sending off. It really livened it up.
United can moan all they want, but they are just deflecting blame from themselves. They reacted terribly to the red card for 10 mins after it, and by the time they had composed themselves they had lost the game. Many teams have coped well with a man deficit, Chelsea managed to even win in Barcelona with a man down for a full half last season, but United didn't cope well at all. Blaming everything on the ref just masks their own failings (not making enough of their chances, questionable team selection, poor reaction from the players and the manager to the circumstances after the red.)