Short answers, pulled from the story.
NBA owners voted 13-4 to merge with the American Basketball Association on the 18th of June 1970. ABA owners unanimously agreed in an 11-0 vote but the merger stalled before it began due to legal challenges.
The initial merger plan failed because an antitrust suit filed by the NBA Players Association blocked the deal. Oscar Robertson led the lawsuit arguing that the merger would trap players without free agency options and the case remained active for six years until settling on the 3rd of February 1976.
Four ABA franchises joined the NBA under strict terms on the 17th of June 1976 including the Denver Nuggets Indiana Pacers New York Nets and San Antonio Spurs. Each team paid a $3.2 million expansion fee by September 15 while the Nets faced an additional $4.8 million indemnity payment to their rivals the New York Knicks.
The Memphis Sounds folded in November 1975 after changing names from Hustlers to Claws and failing to post a required performance bond. The Utah Stars went bankrupt on the 2nd of December 1975 when owner Bill Daniels lacked funds after losing his campaign for Governor of Colorado.
The three-point field goal existed in the ABA before the NBA adopted it in 1979-80 and the slam dunk contest began at the 1976 ABA All-Star Game. The ABA also tracked blocked shots steals turnovers and individual rebounds beginning in 1967-68 which the NBA replicated gradually over subsequent seasons.