Some questions about Diana Nyad's swim?

Let me preface this by saying that what she did was extraordinary. I do,however, have some technical questions.

They keep saying that she was the first to do the swim without a shark cage. What is the deal with shark cages? Does having a shark cage make the swim easier, or does it just provide added protection from sharks?

Nyad obviously had to eat during the swim. I was always told to wait an hour after eating before going swimming to avoid getting a cramp. How did Nyad manage to avoid cramps?

Pardon this indelicate question, but how do you handle food elimination during such a swim?