It shall be his duty, either personally or by such assistants as he may designate, to perform all services incident to the department of law; to attend all meetings of the board of commissioners; to give advice in writing, when so requested; to the board of commissioners or the director any department; to prosecute or defend, as the case may be, all suits or cases to which the town may be a party; to prepare all contracts, bonds and other instruments in writing in which the town is concerned, and to endorse on each his approval of the form and correctness thereof; and to perform such other duties of a legal nature as the board of commissioners may require. In addition to the duties imposed upon the town attorney by this charter or required of him by ordinance or resolution of the board of commissioners he shall perform any duties imposed upon the chief legal officer of municipalities by law.