Short answers, pulled from the story.
The International Cometary Explorer lifted off on the 12th of August 1978. This launch marked the beginning of a joint effort between NASA and ESRO/ESA to study solar wind interactions with Earth's magnetic field.
The International Cometary Explorer carried no cameras or imaging systems. Its instruments measured energetic particles, waves, plasmas, and fields instead.
Fifteen propulsive maneuvers and five lunar gravity assists ejected the craft into a heliocentric orbit after it left its halo orbit around the Lagrange point on the 10th of June 1982. The spacecraft passed through the plasma tail of comet Giacobini-Zinner on the 11th of September 1985.
Two-way communication was reestablished by the unofficial ISEE-3 Reboot Project on the 29th of May 2014. This group received support from Skycorp company and SpaceRef Interactive.
Later firings of the thrusters failed apparently due to lack of nitrogen pressure in fuel tanks. By the 24th of July 2014, all attempts to change orbit using the propulsion system had failed.