Short answers, pulled from the story.
Copland's peers and critics gave him the title "Dean of American Music" in recognition of his central role in shaping the sound and identity of American classical music. His ballets, orchestral works, and advocacy for younger composers made him the defining figure of his generation.
Nadia Boulanger was a French pedagogue whom Copland studied with for three years at the Fontainebleau School of Music in Paris, having initially switched to her from composer Paul Vidal. She emphasized "la grande ligne" -- a sense of forward motion and structural inevitability -- and her confidence in Copland's talent was, in his own words, "crucial to my development at this time of my career".
Copland's most celebrated works include the ballets Appalachian Spring (1944), Billy the Kid (1938), and Rodeo (1942), as well as Fanfare for the Common Man (1942), Lincoln Portrait (1942), and the Third Symphony. Appalachian Spring won the Pulitzer Prize in composition.
Yes. Because of his support for the Communist Party USA ticket in 1936 and Progressive Party candidate Henry A. Wallace in 1948, Copland was placed on an FBI list of 151 artists with suspected Communist associations. In 1953, A Lincoln Portrait was withdrawn from President Eisenhower's inaugural concert, and Copland was later called to a private hearing at the United States Capitol and questioned by Joseph McCarthy and Roy Cohn. The investigations were formally closed in 1975.
Copland incorporated serial techniques beginning with the Piano Quartet in 1950, after being exposed to the work of Pierre Boulez and the late music of Anton Webern. Unlike Arnold Schoenberg, who used tone rows as complete structural statements, Copland used his rows as sources for melodies and harmonies, much as he handled tonal material. His Piano Fantasy (1957), composed over several years on a commission from pianist William Kapell, was among the most significant results of this approach.
Copland died on the 2nd of December 1990, of Alzheimer's disease and respiratory failure, in North Tarrytown, New York, now known as Sleepy Hollow. His ashes were scattered over the Tanglewood Music Center near Lenox, Massachusetts. Much of his estate was directed toward the Aaron Copland Fund for Composers, which distributes over $600,000 per year to performing groups.