Short answers, pulled from the story.
The Soviet Union launched the first Vega spacecraft on the 15th of December 1984 from Baikonur Cosmodrome in the Kazakh SSR. This launch marked a strategic pivot for the Venera program after American Halley mission plans collapsed in 1981.
Vega 1 arrived at Venus on the 11th of June 1985 while its sister ship Vega 2 reached the planet on the 15th of June 1985. Both vessels released spherical descent units some days before arrival without making active inclination changes during entry.
Both Vega-1 and Vega-2 balloons operated for more than 46 hours from injection until final transmission ceased. Batteries finally died after the balloons moved swiftly across the night side into the light side of the planet.
Vega 1 made its closest approach on the 6th of March 1986 at approximately 10,000 kilometers from the nucleus. Vega 2 followed with its own closest approach on the 9th of March 1986 at roughly 8,000 kilometers distance.
The program represented a cooperative effort among the Soviet Union and Austria, Bulgaria, France, Hungary, East Germany, Poland, Czechoslovakia, and West Germany. An international team processed TV data including scientists from the Soviet Union, Hungary, France, East Germany, and the United States.