Section 15. The first justice of a division may appoint such number of court officers for his division as the administrative justice of the housing court department may from time to time determine. Any such court officer may be removed for any cause considered by the first justice of the division to be sufficient. Any vacancy caused by removal or otherwise may be filled by the first justice of the division. The court officers shall attend the sessions in the divisions of the housing court department, shall preserve order and may serve warrants, mittimuses, precepts, orders and processes of a division of the housing court department. Each court officer shall give bond for the faithful performance of his duties in the sum of one thousand dollars payable to the commonwealth, with sufficient sureties approved by the administrative justice. Each court officer, while on duty in the housing court department, shall wear a uniform approved by the administrative justice which shall be furnished at the expense of the commonwealth.