shall cooperate with the various departments and agencies of the Federal Government;

shall use, to the maximum extent, the existing facilities and resources of the Federal Government and, with their consent, the facilities and resources of the States and political subdivisions thereof, and of other organizations and agencies; and

shall refrain from engaging in any form of activity which would duplicate or parallel activity of any other Federal department or agency unless the Administrator, with the written approval of the President, shall determine that such duplication is necessary to accomplish the purposes of this subchapter.