This pact was created betwen Western Allies and it was based on collective security.

North Atlantic Treaty Organization (NATO), 1949. The North Atlantic Treaty Organization was created in 1949 by the United States, Canada, and several Western European nations to provide collective security against the Soviet Union.

yes i think there would be volunteers

this means that germany had to pay the allied countries. reparations are/is essentially payment for something that they have done wrong, so after ww1, germany was forced to pay reparations so they could replenish the allied countries resources' that they had lost during the war.