Four Freedoms Speech: Questions

Why did FDR find it necessary to spend so much time reviewing moments of American history in his lead-up to revealing the Four Freedoms? What was his purpose? What does that imply about his audience?
In the "Four Freedoms" speech, FDR asks a lot of people to make a lot of sacrifices. Does he adequately justify and explain his request? It might seem obvious to us now, knowing the history of World War II, but try to imagine being an American in 1941 who'd lived through the Great Depression.
How do you think FDR determined exactly what the Four Freedoms are? Did he leave anything out?
FDR often uses vague language to refer to very real events. Why does he do this? Is it just his personal style? Does it add to or take away from the impact of his speech?
Pretend you're a supporter of U.S. isolationism in 1941. How might you respond to FDR's "Four Freedoms" speech? What kind of counter arguments can you make?
If FDR suspected that spies had already infiltrated the United States, why did he still broadcast a speech about providing war materials to democratic nations? What kind of effect would this have had on the American public?
What does FDR mean when he says, "The best way of dealing with the few slackers or trouble makers in our midst is, first, to shame them by patriotic example, and, if that fails, to use the sovereignty of government to save government" (108)?