The whole Naruto growing up story has soo many questions. First of all,why Naruto? How come they didn't choose another baby? That must mean that his parents signed off on it. Which leads me to believe that Naruto is the 4th's son.
I believe that the 4th is still alive. There are too many questions and no real proof of anything. There was a theory thread that said the 4th is the leader of Atatsuki and his wife is his 2nd. I believe it. Never saw the theory? here it is