On and after the first day of July, 1970, the Municipal governing body, as then and theretofore constituted, and its administrative officers, shall continue to exercise the powers and duties given them by the Charter under which they were elected and appointed and shall, in addition thereto, exercise such powers and duties as are given to and imposed upon them by this Charter, expressly or impliedly, for conducting the first primary and general elections under this Charter. The members of said existing Municipal governing body shall so serve until the first officers elected under this Charter shall have been elected and qualified, at which time their terms shall end.