Short answers, pulled from the story.
The Halley Armada consisted of five successful space probes that converged on Halley's Comet during its 1986 passage. The group included one probe from the European Space Agency, two joint projects between the Soviet Union and France, and two probes from Japan's Institute of Space and Astronautical Science.
Giotto flew within 596 kilometers of Halley's center on the 14th of March 1986. This close approach allowed the probe to capture the first close-up color images of a comet nucleus ever taken by human technology.
Vega 2 passed within 8,030 kilometers of Halley while approaching the comet on the 9th of March 1986. Both Vega spacecraft dropped balloon probes onto Venus before continuing their journey toward the comet as part of the Intercosmos program.
NASA abandoned all planned contributions to the Halley observation campaign following the Space Shuttle Challenger disaster on the 28th of January 1986. That launch failure resulted in the cancellation of subsequent shuttle missions including STS-61-E scheduled for the 6th of March 1986 which would have deployed ASTRO-1 observatory.
Existing spacecraft like Pioneer 7 monitored Halley's Comet from distant vantage points throughout 1986 after launching on the 17th of August 1966. The International Cometary Explorer also transited between the Sun and Halley in late March while Pioneer Venus Orbiter provided additional measurements during Halley's perihelion on the 9th of February 1986.