The district shall do all the following:
(a) Adopt an annual budget.
(b) Adopt an administrative code, by ordinance, which prescribes the powers and duties of the district officers, the method of appointment of the district employees, and methods, procedures, and systems of operation and management of the district.
(c) Cause a postaudit of the financial transactions and records of the district to be made at least annually by a certified public accountant.
(d) Do any and all things necessary to carry out the purposes of this part.