(a) All moneys derived from the sale of any bonds issued by the authority shall be used solely for the purpose or purposes for which the same are authorized, including costs and expenses of issue. Such costs and expenses may include but shall not be limited to:

(1) The fiscal, legal and other expenses incurred in connection with the issuance of the bonds; and

(2) Except in the case of refunding bonds, interest to accrue on such bonds for a period ending not later than two years from their date.

(b) Bonds shall be issued in series, each of which shall be separately designated in the proceedings authorizing their issuance. The board of directors in the proceedings authorizing a series of bonds (other than refunding bonds) shall specify the purposes for which the proceeds of such series shall be used. The proceeds of a series of bonds shall be used either for making, directly or indirectly, single family mortgage loans or for making, directly or indirectly, multi-family mortgage loans or for making, directly or indirectly, home improvement loans for eligible existing single family housing units, and the proceeds of a single series of bonds shall not be used for any combination of single family mortgage loans, multi-family mortgage loans and home improvement loans. Separate series of bonds may be issued at the same time. No series of bonds, the proceeds which are to be used for multi-family mortgage loans, shall be actually issued prior to January 1, 1981, although the authority may enter into agreements or commitments with regard to the issuance of such bonds prior to January 1, 1981.

(c) In the proceedings authorizing any bonds (other than refunding bonds) the proceeds of which are to be applied, directly or indirectly, to the making of single family mortgage loans, the board of directors shall specify the portion of the proceeds thereof which the board of directors has determined are to be used for the purpose of providing funds with respect to the making, directly or indirectly, of such mortgage loans, and of such portion shall allocate (1) a minimum of 70 percent of such proceeds to the making of mortgage loans with respect to new and previously unoccupied eligible housing units, and (2) not exceeding 30 percent of such proceeds to the making of mortgage loans for existing eligible housing units and for the purchase of existing mortgage loans with respect to eligible housing units; provided, however, that if the authority determines, after 60 days from the date of issuance of any series of bonds issued for the purpose of financing single family mortgage loans, that the proceeds of such series have not been expended or committed to be expended for mortgage loans with respect to new and previously unoccupied eligible housing units, then such proceeds may be used to finance any single family mortgage loans.

(d) If, for any series of bonds the proceeds of which are to be used for making, directly or indirectly, single family mortgage loans, the total requests for mortgage funds by mortgage lenders at the interest rate nearest to the mortgage interest rate actually obtained by the bond issue are less than or equal to an amount equal to the maximum principal amount of mortgage revenue bonds which may be issued under federal law during the then-current calendar year, then the authority shall allocate the net proceeds available for mortgage loans in such manner as it shall determine in its sole discretion.

(e) If, for any series of bonds the proceeds of which are to be used for making, directly or indirectly, single family mortgage loans, the total requests for mortgage funds by mortgage lenders at the interest rate nearest to the mortgage interest rate actually obtained by the bond issue exceed an amount equal to the maximum principal amount of mortgage revenue bonds which may be issued under federal law during the then-current calendar year, then 35 percent of the net proceeds available for mortgage loans shall be allocated equally among the 67 counties of the state for a period of 60 days commencing on the date of issuance of such series of bonds. The authority, in its sole discretion, shall have the option to extend such 60-day period for an additional 30 days, and the further option to extend such period for an additional 30 days. At the expiration of such period, including any extension thereof, the authority may reallocate in the manner provided in subsection (d) of this section any portion of any county's original allocation which is not the subject of a written commitment for mortgage loans by mortgage lenders. The remaining 65 percent of such net proceeds shall be allocated by the authority in the manner provided in subsection (d) of this section.