Each such agreement shall (1) specify its terms, (2) the proportionate interest which each municipality shall have in the property, facilities and privileges involved, (3) the proportion of the preliminary costs, costs of acquisition, establishment, construction, enlargement, improvement and equipment, and of the expenses of maintenance, operation and regulation to be borne by each, (4) make such other provisions as may be necessary to carry out the provisions of sections 3-221 to 3-232, (5) provide for amendments thereof, (6) the conditions and methods of termination and (7) the disposition of all or any part of the property, facilities and privileges jointly owned if said property, facilities and privileges, or any part thereof, shall cease to be used for the purposes herein provided or if the agreement shall be terminated, and for the distribution of the proceeds received upon any such disposition, and of any funds or other property jointly owned and undisposed of, and the assumption or payment of any indebtedness arising from the joint venture which remains unpaid, upon any such disposition or upon a termination of the agreement.