(a) Bonds may be sold and negotiated in any market after due advertisement and may be made callable as the board of directors may direct.
(b) The bonds so issued shall be signed by the president of the board and countersigned by the secretary.
(c) The bonds shall bear interest at a rate not exceeding an average of three and one-half percent (3½%) per annum, over the period of the life of the bonds, represented by semiannual coupons.
(d) The place of payment and the amount of the several installments to be paid each year may be fixed by the board.
(e) The interest coupons shall be authenticated by the lithographed signature of the president of the board.