In addition to the #3 - Get the book 'Disease Proof Your Child' from Dr. Fuhrman, http://www.drfuhrman.com If you tell him I sent you in the comments section he sometimes autographs it. It is a great book on foods that kids should be eating.
He says to get rid of all cereals in the house and gradually make changes to what is available. Children can only eat what their parents provide for them to a point. After you make some changes you start to provide the good things that you know they like. You find out more and more of what they like by providing lots of healthy products. Typically, also, a 'stubborn' child is they result of a parent providing too much crap over the years. Even the stubbornest of kids will eat the good stuff eventually if that's all you provide.