1) Terrorists bomb over 50 malls in the United States at the same time (or as many as they can, followed by bomb threats all over the nation), with the purpose of damaging the economy and promoting fear; and increase illegal drug sales/use, with the purpose of promoting a breakdown of the people. Fear, rioting, and a collapse of honor and values among the Americans is the only way terrorists can win. Terrorists vs America will never win, but terrorists, with help from the American people, have a chance. They have to figure out how to help us destroy ourselves, they realize that's the only way to bring about our destruction - from within.
2) I think it depends on who the most powerful people are at the time.
3) The President will say what he thinks the people need to hear. He will say things to help calm fears, and comfort the grieving. And he will say what he thinks should be done as far as retaliation. History has shown that most of this is based on the President as an individual and his staff.
How will they use this on a continuing basis? They will observe and speculate on how the people can destroy themselves. How can they promote that? What can they do that will promote a response that will start a destruction internally?