Sec. 18. (1) In addition to the bonds authorized in section 14, bonds may be issued for the purpose of acquiring, constructing, improving, enlarging, extending, operating, or financing facilities or refunding prior indebtedness of the authority, as follows: (a) By the issuance of bonds under contracts described in section 13 under which a constituent unit has pledged its full faith and credit and, if necessary, has agreed to pay to an authority certain sums toward the cost of the acquisition, construction, improvement, enlargement, extension, operation, or financing of a project or refunding of prior bonds that may be made under this act. Contracts are not subject to the revised municipal finance act, 2001 PA 34, MCL 141.2101 to 141.2821. (b) By money advanced by an authority operating under this act under agreements with a constituent unit or other unit for the repayment of the money. (c) By money advanced, from time to time, before or during construction of a project, by a public corporation, for which an authority operating under this act shall reimburse the corporation with interest not to exceed 8% per annum or without interest as may be agreed, when funds are available for reimbursement. The obligation of an authority to make the reimbursement may be evidenced by a contract or note and the contract or note may be made payable out of the payments to be made by constituent units under contracts made under subdivision (b), out of the proceeds of bonds issued under this act by the county, or out of any other available funds. (2) Bonds issued under this section must be authorized by a resolution adopted by the authority. The bonds must be issued in the name of the authority and must be executed by the chairperson and secretary-treasurer of the authority, who shall also cause their facsimile signatures to be affixed to the interest coupons to be attached to the bonds. The authority shall adopt a seal that must be affixed to the bonds. Bonds issued under this section are negotiable instruments and must mature not more than 40 years after the date of issuance. The bonds and coupons must be made payable in lawful money of the United States and are exempt from all taxation by this state or by any taxing authority within this state. (3) Bonds or notes issued under this section are subject to the revised municipal finance act, 2001 PA 34, MCL 141.2101 to 141.2821.