(1) The powers conferred by this part shall be in addition and supplemental to the powers conferred by any other law, and are not in substitution for those powers, and the limitations imposed by this part shall not affect those powers.
(2) The powers granted in this part may be exercised without regard to requirements, restrictions or procedural provisions contained in any other law or charter, except as expressly provided in this part.
(3) Any metropolitan government or any home rule municipality authorized under this part to create a water and wastewater treatment authority may do so without the necessity of a charter amendment, notwithstanding anything in its charter to the contrary.