Brilliant analysis. Another thing I've learned and it ties in with your dialogue series is that what a person says and does can contradict. In my current script the protag says he'll do this for his friends but the action contradicts this, instead the character is selfish throughout the film until the end.

Glad to see you discussing one of my favorite scripts. It's also interesting to note the way Crowe uses the recurring 'Dicky Fox' cameos both to set the basic ethos of Jerry's profession and, ultimately, to provide a wonderful coda. Not many movies use this device, but when it works, there's nothing better.
The film is essentially over, at least as regards the plot -- Jerry has won, and and Dorthy are back together and her son is showing precocious signs of athletic ability (after that long-promised trip to the zoo, no less). Most writers would be content to end the film right there, in the park, with the protagonists literally walking off in to the sunset.
But Crowe has another card to play: Dicky Fox.
We see him one last time, and he sums up the whole movie for us:

"Hey, I don't have all the answers. In life, to be honest, I failed as much as I have succeeded. But I love my wife. I love my life. And I wish you my kind of success."

The perfect finishing touch to a perfect film.