In addition to revenue derived by tax levy, the board of hospital trustees of a merged area shall be authorized to receive and expend:
1. Federal funds which may be available by federal laws, rules and regulations.
2. State aid which may be available by state laws and rules.
3. Fees and expenses charged to persons using the facilities of the hospital.
4. Donations and gifts which may be accepted by the hospital trustees and expended in accordance with the terms of the gift without compliance with the local budget law, chapter 24.