Short answers, pulled from the story.
Harvard terminated Leary in 1963 for failing to attend his scheduled class lectures, though the decision was also influenced by his promotion of psychedelic drug use among students and faculty. His salary was cut on the 30th of April 1963, and Harvard President Nathan Pusey publicly stated that Leary had left campus without authorization. His colleague Richard Alpert was dismissed separately for allegedly providing psilocybin to an undergraduate off campus.
According to his son Zachary, Leary's final moments produced the repeated phrase "Why?" followed by "Why not?" His last word, Zach reported, was "beautiful". His death on the 31st of May 1996, was videotaped at his own request by Denis Berry and Joey Cavella.
Leary escaped in September 1970 by climbing a telephone wire over the wall of a lower-security prison to which he had been assigned after strategically answering his intake psychological tests. The Weathermen then smuggled him out of the United States in a pickup truck driven by Clayton Van Lydegraf, for a fee of $25,000 paid by the Brotherhood of Eternal Love.
Leary's eight-circuit model divides human consciousness into eight levels. The first four, called the Terrestrial Circuits, are naturally accessed at life transitions such as puberty. The upper four, called the Extra-Terrestrial Circuits, were described as evolutionary adaptations that would prepare humans for life in space. The model was developed with writer Brian Barritt and fully published in 1977 in Leary's book Exo-Psychology and in Robert Anton Wilson's Cosmic Trigger.
Leary coauthored The Psychedelic Experience in 1964, which directly inspired John Lennon's song "Tomorrow Never Knows" on The Beatles' 1966 album Revolver. Leary also recruited Lennon to write a campaign song for his California gubernatorial race against Ronald Reagan; that song became "Come Together" in 1969. Leary was present and sang backing vocals when Lennon and Yoko Ono recorded "Give Peace a Chance" at their Montreal bed-in.
Seven grams of Leary's ashes were launched into orbit on the 21st of April 1997, aboard a Pegasus rocket alongside the remains of Star Trek creator Gene Roddenberry, space colonization advocate Gerard O'Neill, and rocket engineer Krafft Ehricke. The rocket remained in orbit for six years before burning up in the atmosphere. In 2015, Susan Sarandon brought a portion of his ashes to the Burning Man festival in Black Rock City, Nevada, where they were burned in an art installation on the 6th of September 2015.