(1) Any party to a full adjudicative proceeding may participate personally.

(2) The owner of the majority interest in a certified business is a necessary party and shall appear on behalf of the business.

(3) A former employee of the office shall not, at any time after severing his or her employment with the office, appear as a representative or expert witness on behalf of a petitioner in a matter in which he or she previously took an active part as a representative of the office, except with the written permission of the director.