Bonds and notes which have been authorized under this article may be issued from time to time and shall be sold at not less than par and accrued interest at public or private sale by the chairman of the school board and by the treasurer. Interstate district bonds and notes shall be signed by the said officers, except that either one of the 2 required signatures may be a facsimile. Subject to this compact and the authorizing vote, they shall be in such form, bear such rates of interest and mature at such times as the said officers may determine. Bonds shall, but notes need not, bear the seal of the interstate district, or a facsimile of such seal. Any bonds or notes of the interstate district which are properly executed by the said officers shall be valid and binding according to their terms notwithstanding that before the delivery thereof such officers may have ceased to be officers of the interstate district.   [PL 1981, c. 693, §§ 5, 8 (NEW).]