Section 18. Except as otherwise provided in this section, the legislative powers of the city council may be exercised as provided by ordinance or rule adopted by it.

1. Every member of the council may vote on any question coming before it. A majority of the council shall constitute a quorum, and the affirmative vote of a majority of all the members of the council shall be necessary to adopt any motion, resolution or ordinance.

2. The city council shall, from time to time, establish rules for its proceedings. Regular and special meetings of the council shall be held at a time and place fixed by ordinance. Except as otherwise authorized by section twenty-three A of chapter thirty-nine, all sessions of the council shall be open to the public and to the press, and every matter coming before the council for action shall be put to a vote, the result of which shall be duly recorded. A full and accurate journal of the proceedings of the council shall be kept, and shall be open to the inspection of any registered voter of the city.

3. The council shall, by a majority vote, elect a city clerk to hold office for three years and until his successor is qualified. He shall have such powers and perform such duties as the council may prescribe, in addition to such duties as may be prescribed by law. He shall keep the records of the meetings of the council.

The person holding the office of city clerk at the time when any of the plans set forth in this chapter has been adopted by such city shall continue to hold office for the term for which he was elected and until his successor is qualified.

4. The council in any city adopting Plan D or E shall, by a majority vote, elect a city auditor to hold office for three years and until his successor is qualified. He shall keep and have charge of the accounts of the city and from time to time audit the books and accounts of all departments, commissions, boards and offices of the city, and shall have such other powers and perform such other duties as the council may prescribe, in addition to such duties as may be prescribed by law.