If two-thirds (2/3) of the qualified electors of the county voting at such election vote in favor of the issuance of the bonds, the board of commissioners shall select and purchase, or, if necessary, cause to be condemned, for the use of the county, a suitable site for said buildings, and cause to be prepared plans and specifications for such courthouse and jail, or either thereof as the case may be, and advertise in a weekly newspaper of the county for thirty (30) days calling for sealed proposals or bids for the construction of said buildings. The published notice shall contain a general statement of the character and limited cost of the building or buildings, and state that the plans and specifications thereof may be found and examined in the office of the clerk of the board, and state the day when the sealed proposals will be opened and considered. The sealed proposals must be opened and considered publicly, and the contract let to the lowest responsible bidder, unless all bids are rejected; and if all bids are rejected, the board may advertise for new bids, or let the contract, provided it be for a less sum than that offered by the lowest bidder. The board must require a good and sufficient bond of the contractor conditioned for the faithful performance of the contract according to the plans and specifications. The board shall have full power and authority to do and perform any act in relation to purchasing such site and erecting said buildings, at any special or called meeting when all members of the board are present, or at any regular meeting of the board.