Short answers, pulled from the story.
Shostakovich had a deeply conflicted relationship with the Soviet government. He was formally denounced twice, first in 1936 when Pravda attacked Lady Macbeth of the Mtsensk District, and again in 1948 under the Zhdanov Doctrine. Despite this, he held official positions including membership in the Supreme Soviet of the USSR from 1962 until his death, and was chairman of the RSFSR Union of Composers from 1960 to 1968.
The First Symphony was premiered on the 12th of May 1926, conducted by Nikolai Malko with the Leningrad Philharmonic Orchestra. Shostakovich wrote it as his graduation piece at age 19. The audience demanded an encore of the scherzo, and the symphony brought Shostakovich international recognition; Bruno Walter conducted its first performance outside Russia later that year, and Leopold Stokowski led the American premiere in Philadelphia.
The Zhdanov Doctrine was a 1948 Soviet decree targeting composers accused of formalism and Western compositional influence. Andrei Zhdanov, Chairman of the Supreme Soviet of the RSFSR, accused Shostakovich, Prokofiev, and Khachaturian, among others, of writing inappropriate music. Most of Shostakovich's works were banned, he was dismissed from the Conservatory, his family's privileges were withdrawn, and he was forced to make a public apology.
Testimony, published in 1979, claimed to be Shostakovich's memoirs as dictated to Volkov, and alleged that many of his works contained coded anti-government messages. Musicologist Laurel Fay's 2002 article "Volkov's Testimony reconsidered" showed that the only manuscript pages Shostakovich had signed were word-for-word reproductions of earlier interviews he had given. Shostakovich's son Maxim initially disputed the book's authenticity in 1981 but has spoken more favorably about it since the Soviet regime fell in 1991.
Shostakovich composed 15 symphonies and 15 string quartets over the course of his career. The symphonies are distributed fairly evenly across his working life, while the quartets are concentrated toward his later years. Among his most popular works are the Fifth and Seventh Symphonies and the Eighth and Fifteenth String Quartets.
Shostakovich wrote the first three movements of the Seventh Symphony while Leningrad was under siege in 1941, then completed the work after being evacuated to Kuybyshev. When the symphony was performed in besieged Leningrad in August 1942, conductor Karl Eliasberg found only 14 musicians remaining in the city's orchestra and had to recruit anyone capable of playing an instrument to fill the ensemble.