Mockingjay contains several references to the fact that Panem is built on the ruins of the former United States. How does this tie into the theme of cyclical abuses of power?

How are Katniss and Gale’s attitudes toward killing informed by the fact that Katniss has competed in the Hunger Games and Gale hasn’t?

How does Katniss’s understanding of morality evolve as she matures into young adulthood? How is her conception of right and wrong affected by living through a civil war?