Short answers, pulled from the story.
The Cominform was the Information Bureau of the Communist and Workers' Parties, a coordination body for Marxist-Leninist parties across Europe that existed from 1947 to 1956. It was created to exchange information and coordinate the activities of nine European communist parties under Soviet direction, and it specifically tasked the French and Italian communist parties with obstructing the Marshall Plan and the Truman Doctrine in Western Europe.
Cominform was officially established on the 5th of October 1947. Its founding conference took place on the 22nd and the 23rd of September 1947 in Jelenia Gora, Poland, following an earlier informal gathering in Szklarska Poreba, Poland. Its original headquarters were in Belgrade, Yugoslavia.
Yugoslavia was expelled from Cominform at the third meeting on the 28th of June 1948 for what was officially called Titoism and anti-Sovietism. The resolution accused the Yugoslav Communist Party of pursuing a line appropriate only to nationalism and representing a departure from Marxism-Leninism. A significant underlying factor was Yugoslavia's support for communist forces in the Greek Civil War, which violated the Percentages Agreement between the Soviet Union and the United Kingdom.
The Cominform's press organ was titled For a Lasting Peace, for a People's Democracy! It was published as a fortnightly journal in Russian, French, and English. It was first issued in Belgrade on the 1st of November 1947, and after Yugoslavia's expulsion the paper moved to Bucharest along with the organization's headquarters.
Cominform was officially dissolved on the 17th of April 1956 by a decision of the Central Committee of the CPSU. The dissolution was prompted by Soviet rapprochement with Yugoslavia and the de-Stalinization process following the rise of Nikita Khrushchev. By that point the body had already been largely superseded by Comecon, founded in 1949, and the Warsaw Pact, formed in 1955.
Cominform was founded with nine member parties: the Communist Party of the Soviet Union, the Bulgarian Communist Party, the Communist Party of Czechoslovakia, the Hungarian Communist Party, the Polish Workers' Party, the Romanian Communist Party, the Communist Party of Yugoslavia, the French Communist Party, and the Italian Communist Party. Yugoslavia was expelled in 1948, reducing the membership to eight.