As soon as possible after the creation of an Authority the commissioners shall organize for the transaction of business by choosing from among their number a chairman and a vice-chairman and by adopting by-laws and rules and regulations suitable to the purposes of this Act. Three commissioners shall constitute a quorum for the transaction of the business of an Authority that has 5 commissioners, 4 commissioners shall constitute a quorum for an Authority that has 7 commissioners, and 6 commissioners shall constitute a quorum for an Authority that has 10 commissioners. The commissioners shall, from time to time, select and appoint a chief executive officer and officers and employees, including engineering, architectural and legal assistants, as they may require for the performance of their duties, and may prescribe the duties and compensation of each officer and employee or expressly delegate that authority to the chief executive officer.