(a) In addition to the other rulemaking requirements imposed by law, each agency shall:
(1) Adopt as a rule a description of its organization, stating the general course and method of its operations and the methods whereby the public may obtain information or make submissions or requests;
(2) Adopt rules of practice setting forth the nature and requirements of all formal and informal procedures available, including a description of all forms and instructions used by the agency;
(3) Make available for public inspection and copying, at cost, all rules and all other written statements of policy or interpretations formulated, adopted or used by the agency in the discharge of its functions;
(4) Make available for public inspection and copying, at cost, and index by name and subject all final orders, decisions, and opinions which are issued after October 1, 1982, except those expressly made confidential or privileged by statute or order of court.
(b) No agency rule, order, or decision shall be valid or effective against any person or party nor may it be invoked by the agency for any purpose until it has been made available for public inspection and indexed as required by this section and the agency has given all notices required by Section 41-22-5. This provision is not applicable in favor of any person or party who has actual knowledge thereof, and the burden of proving such knowledge shall be on the agency.