Great decision by the referee. Neymar wasn't pulled down and just did a slow motion backflip,
Shame
Why no yellow for diving?
... but well deserved.
Good question, although you could say there was a tug on the shirt. But I don't think that was in any way the cause of him falling.
Should also have had a yellow for deliberate handball after his little party trick. He controlled the ball with his arm after flicking the ball over his head.