(1) Except as provided by law, a first class school district has all of the powers granted to a general powers school district in section 11a and has all additional powers granted by law to a first class school district or the board of a first class school district.

    (2) Unless expressly provided in the amendatory act that added this section, the powers of a first class school district are not diminished by this section or by the amendatory act that added this section.