(1) A rule may be declared invalid or inapplicable in an action for declaratory judgment if it is found that the rule or its threatened application interferes with or impairs or threatens to interfere with or impair the legal rights or privileges of the plaintiff.
(2) A rule may also be declared invalid in the action on the grounds that the rule was adopted with an arbitrary or capricious disregard for the purpose of the authorizing statute as evidenced by documented legislative intent.
(3) A declaratory judgment may be rendered whether or not the plaintiff has requested the agency to pass upon the validity or applicability of the rule in question.
(4) The action may be brought in the district court for the county in which the plaintiff resides or has a principal place of business or in which the agency maintains its principal office. The agency must be made a party to the action.