(a) The board may prescribe:
(1) the method and manner of making purchases and expenditures by and for the district; and
(2) all accounting and control procedures.
(b) The district shall pay the salaries and expenses necessarily incurred by the board or by an officer or agent of the board in performing a duty prescribed or required by this section or Section 1109.155.
(c) An officer, employee, or agent of the board shall perform any function or service prescribed by the board under this section or Section 1109.155.