(a) The board shall impose a tax on all property in the district subject to district taxation.
(b) The tax shall be imposed for and may be pledged to:
(1) meet the requirements of district bonds;
(2) provide for the district's maintenance and operating expenses, including the cost of contract payments for hospital care for needy district inhabitants;
(3) make improvements and additions to the district's hospitals or hospital system; and
(4) acquire necessary sites for hospitals or the hospital system by gift, purchase, lease, or condemnation.