(a)   Chief administrative officer.  The department head shall be the chief administra-tive officer of the department, subject to departmental policies, the supervisory authority of the mayor as to administration and policy directives of the board of aldermen or policies established by boards and commissions in accordance with section 2.04 of this charter.
   (b)   Exclusive personnel responsibility.  The department head shall have exclusive personnel authority within the department. All appoint-ments and promotions shall be made solely on the basis of merit and only after appropriate examination or review of the applicant's relative knowledge, skills, abilities and experience. Hiring, assignment, promotion, and discipline of personnel within the department shall be subject to the requirements of personnel ordinances and the provisions contained in collective bargaining agreements.
   (c)   Supervisory authority.  The department head shall supervise the activities of the department and its employees and shall maintain a proper record of such activities, including money expended.
   (d)   Budgetary authority.  The department head shall prepare such budget and program plans and requests as may be necessary for the operation and development of the department. The department head shall submit the same to the mayor for inclusion in the city budget, all in accordance with guidelines set by the mayor.
   (e)   Small purchase expenditures.  The department head shall be responsible for budget expenditures made under the small purchase procedures of this charter or ordinances of the city.