With respect to any bonds the district board shall prescribe the denominations of the bonds, the size of each issue and the form of the bonds and shall establish the maturities, interest payment dates and interest rates, whether fixed or variable, not exceeding the maximum rate stated in the notice of the election or the resolution of the district board. The bonds may be sold by competitive bid or negotiated sale for public or private offering at, below or above par. If the bonds are sold below par, the aggregate amount of discount and interest to be paid on the bonds shall not exceed the amount of interest that would have been payable on those bonds pursuant to the maturity schedule prescribed by the district board at the maximum rate set out in the bond resolution. The proceeds of the sales shall be deposited with the treasurer, or with a trustee or agent designated by the district board, to the credit of the district to be withdrawn for the purposes provided by this article. Pending that use, the proceeds may be invested as determined by the district. The bonds may contain such terms, conditions, covenants and agreements as the district board deems proper. The bonds may be payable from any combination of revenues or special assessments of the types described in this article and as specified in the bonds if all applicable requirements are met.