Does Catherine Middleton have to curtsy to the Queen?
Everyone does officially. She won't be doing it everytime she sees her though, just when it's called for.When the Queen used to travel visiting her commonwealth countries upon returning everyone was to wait in a line and great her formally even her own children. Charles had to bow to his mother. Another thing she apparently didn't like about Princess Diana, when she returned from trips away to draw attention to removing land mines, Diana would throw open her arms and her boys would run into her arms and she would scoop them all giving cuddles and kisses, the Queen thought it not how a Royal should act.
Why did Queen Elizabeth II allow Prince William to marry Catherine Middleton, a commoner? Aren’t they only allowed to marry nobles?
There's absolutely no law, written or otherwise, that a royal must marry another royal or even a member of the aristocracy. Following the disastrous marriages of three of her four children, she was probably only more than happy to give her consent to the marriage, regardless of the fact that Catherine was "merely" the daughter of self-made millionaires. William and Catherine had had a very long courtship and were clearly compatible and in love, and that's what matters in a successful marriage -- especially one in the public eye -- not whether both parties came into the marriage with a title.And the Queen's own mother was a commoner, by the way. Yes, she was a member of the aristocracy, as her father was an earl, but she was still a commoner, as she wasn't royal (prior to her marriage, obviously). Ditto for Diana.