The operational civil defense and emergency management organization of the municipality shall consist of the officers and employees of the municipality designated by the Emergency Management Director as well as all volunteer workers. The functions and duties of this organization shall be distributed among such divisions, services and special staff as the Council shall prescribe by resolution or the Emergency Management Director shall provide by directive. Any such resolution or directive shall set forth the form of organization, establish and designate divisions and services, assign functions, duties and powers, and designate officers and employees to carry out the provisions of this chapter. Insofar as possible, the form of organization, titles and terminology shall conform to the recommendations of the Texas Defense and Disaster Relief Council and of the Federal Emergency Management Agency.