In counties of 70,000 population or less, as determined by the last federal census preceding the date of appointment, the presiding officer of the county board with the advice and consent of the county board may appoint and employ a county auditor whose term of office shall be 4 years and until a successor is appointed and qualified. Every county auditor appointed pursuant to the provisions of this Section shall hold office until the first Tuesday of May, 1961, and until a successor is appointed and qualified. A successor shall be appointed and take office on the first Tuesday of May, 1961, and every 4 years thereafter, for a term of 4 years and until another successor is appointed and qualified. The qualifications and oath of office of such county auditor shall be the same as apply to other county officers. Each county auditor shall, before entering upon the duties of the office, give bond in such penalty and with such security as the county board shall deem sufficient, which bond shall be substantially in the form required by law to be given by the county clerk. Said bond shall be filed with the county clerk on or before the date the county auditor enters into the duties of the office. In case of a vacancy in the office of county auditor caused by death, resignation, or removal from office, the vacancy shall be filled by appointment by the presiding officer of the county board with the advice and consent of the county board. If the auditor is temporarily unable to perform his or her duties for any reason, the deputy auditor, if there is one, shall assume the duties of the auditor until the auditor is able to resume his or her duties or until a replacement for the auditor is chosen.