The civil service commission, within the terms of this act, shall:

  (1) Adopt and enforce rules and regulations for carrying into effect the provisions of this act. All rules so prepared may be added to, amended or rescinded.

  (2) Keep minutes of its own proceedings and records of its examinations and other official actions. All recommendations of applicants for office, received by the commission or by any officer having authority to make appointments to office, shall be kept and preserved for a period of 10 years; and all such records, recommendations of former employers accepted, and all written causes of removal, filed with it, subject to reasonable regulation, shall be open to public inspection. It shall keep a roster of the members of the department, together with a record of service, military or naval experience, file statements on all matters relating to the character and quality of the work done and the attitude of the individual to his work and such other matters as may have a bearing on promotion, transfer or discharge.

  (3) Make investigations concerning all matters touching the enforcement and effect of the provisions of this act and the rules and regulations prescribed thereunder, and concerning the action of any examiner or subordinate of the commission or any person in the public service in respect to the execution of this act; and in the course of such investigations any commissioner may administer oaths and affirmations and take testimony.

  (4) Make an annual report to the board of supervisors showing its own action, and rules and regulations with all exceptions thereto in force, the practical effects thereof, and any suggestions it may approve for the more effectual accomplishments of the purpose of this act. The reports shall be available for public inspection 5 days after the same shall have been delivered to the board of supervisors.