Short answers, pulled from the story.
Expo 58 was held on the Heysel/Heizel Plateau in Brussels, Belgium, from the 17th of April to the 19th of October 1958. The site was located seven kilometres north-west of central Brussels and covered two square kilometres.
Expo 58 attracted some 41.5 million visitors, making it the second largest world's fair on record at the time. Only the 1900 Exposition Universelle in Paris drew more visitors, with 48 million.
The Belgian Ministry of Colonies exhibited 598 Congolese people in a village indigène intended to display Belgian colonialism's "civilizing" work. The participants, who were educated urbanites, were made to dress in primitive clothing and guarded from communicating with white Belgians. In mid-July they protested and demanded to be sent home, abruptly ending the exhibit. Eight-month-old Juste Bonaventure Langa died during the exhibit and is buried in Tervuren Cemetery.
The Atomium is a giant model of a unit cell of an iron crystal, with each sphere representing an atom, built for Expo 58. It was originally intended to stand for only the six months of the exhibition and then be dismantled, but it was never taken down. Its outer coating was renewed on the fiftieth anniversary of the fair.
The Czechoslovak pavilion was officially awarded best pavilion of Expo 58 and was visited by six million people. It featured the Laterna Magika show and Josef Svoboda's Polyekran, with creative freedom protected by government committee chairman František Kahuda within the constraints of the 1950s communist regime.
Mozart's autograph manuscript of the Requiem was placed on display at Expo 58, and someone tore off the bottom right-hand corner of the second-to-last page, folio 99r/45r, containing the words "Quam olim d: C:". The perpetrator has never been identified and the fragment has not been recovered.