(a) All contractors shall be required to give bond for the faithful performance of the contracts awarded them, with good and sufficient securities, in an amount to be fixed by the board. The board shall not remit or excuse the penalty or forfeiture of the bond or the breaches thereof.
(b) The board may:
(1) Appoint all necessary agents for carrying on the work and fix their pay;
(2) Buy and sell all necessary material and implements as may be on hand, which may not be necessary for the completion of the improvement under way, or which may have been completed;
(3) Make all such contracts in the prosecution of the work as may best subserve the public interest.
(c) It shall be the duty of the board to have the amount of work done by any contractor estimated, from time to time as may be desirable, by the engineer selected by the board. The board shall draw its warrants in favor of the contractor for not more than ninety percent (90%) of the amount of work so reported, reserving the remainder until it has been ascertained that the work has been completed according to contract and is free from liens.