How does the interaction between Helmer and Nora affect the plot?

Nora realizes that Helmer's actions are intended to preserve his masculinity, not their marriage.
Nora realizes that, no matter what the letter says, Helmer will still love her as much as he does now.
Nora comes to understand that Doctor Rank is more important to Helmer than she is.
Nora comes to understand that Helmer wants to share more responsibilities in the marriage now.