Short answers, pulled from the story.
Styx was discovered using the Hubble Space Telescope and its discovery was announced on the 11th of July 2012. The find was made by a team led by astronomer Mark R. Showalter, using fourteen sets of images taken between the 26th of June and the 9th of July 2012.
Styx has an elongated shape with dimensions of approximately 16 by 9 by 8 km. It is the smallest of Pluto's five known moons.
Styx has an orbital period of 20.16155 days. It orbits the Pluto-Charon barycenter at a distance of 42,656 km, placing it between the orbits of Charon and Nix.
On the 2nd of July 2013, the International Astronomical Union formally approved the name Styx for the moon previously designated P5. The name came from a public vote run by Mark Showalter and the SETI Institute in 2013; Styx, the goddess of the underworld river, finished third in the poll but was chosen after the top vote-getter, Vulcan, was rejected by the IAU.
New Horizons flew past the Pluto system on the 14th of July 2015 and obtained only a single image of Styx. Measurements from the flyby confirmed Styx's elongated shape and found no smaller moons or rings in the surrounding region.
Styx is thought to have formed from debris thrown into orbit by a collision between Pluto and another sizable Kuiper belt object in the distant past. The impact is believed to have driven off volatile ices such as nitrogen and methane, leaving a body composed mainly of water ice.