The officers of an authority shall consist of a chairman, vice-chairman, secretary, treasurer and such other officers as its board shall deem necessary or appropriate. The offices of secretary and treasurer may but need not be held by the same person. The chairman and vice-chairman of an authority shall be elected by the board from its membership; the secretary, the treasurer and any other officers of the authority may but need not be members of the board and shall also be elected by the board. The chairman and vice-chairman of the authority shall also be the chairman and vice-chairman of the board, respectively.