On or before July 20, the City Manager shall prepare (after consulting with the heads of the various departments) and submit to Council a budget covering an estimate of available funds and required expenditures for the ensuing calendar year. Council shall, by ordinance, specify the form of and the information to be included in the budget. Such budget may be amended by Council; shall be approved by Council as presented or amended; and shall be the basis of any levy of taxes by Council or any request for an extra levy. Council shall provide for a public hearing on the budget, to be advertised ten days before such hearing.