(a) Bonds issued under this subchapter must mature serially or otherwise not more than 40 years after they are issued. The bonds may:
(1) be sold at a price and under terms that the commissioners court considers the most advantageous reasonably obtainable; and
(2) be made callable before maturity at times and prices prescribed in the order authorizing the bonds.
(b) The bonds may not bear interest at a rate greater than that allowed by Chapter 1204, Government Code.