The state board of land commissioners shall appoint the director of the department who shall have general supervision of all field work, and with such assistants as he, with the approval of the board may appoint, select, locate and appraise all lands which are now, or may be hereafter, granted to this state by the United States for any purpose whatever, and who shall perform the other duties as shall be required of him by the board, or as shall be prescribed by their rules. He shall be paid the salary determined by the board and his actual and necessary expenses while traveling on business of the board. Said director and his assistants shall each take the oath of office and be bonded to the state of Idaho in the time, form and manner prescribed in chapter 8, title 59, Idaho Code. Said assistants shall receive their actual and necessary expenses while traveling on business for the board. The director may employ necessary clerical and other assistants for carrying on the business of the state department of lands and fix their compensation. The director and other appointees of the board shall hold their respective positions during the pleasure of the board.