Short answers, pulled from the story.
Calypso was discovered in 1980 from ground-based observations by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie. It received the provisional designation S/1980 S 25 before being officially named in 1983.
Calypso orbits Saturn at Tethys's trailing Lagrangian point, 60 degrees behind Tethys. This gravitational configuration mirrors the trojan asteroids that trail Jupiter, so Calypso and the moon Telesto are called Tethys trojans.
Calypso has a visual geometric albedo of 1.34, making its surface one of the most reflective in the Solar System. This high reflectivity results from continuous sandblasting by water-ice particles from Saturn's E-ring, which are generated by geysers at the south pole of Enceladus.
Calypso resides in Tethys's trailing Lagrangian point, 60 degrees behind Tethys in Saturn's orbit. The moon Telesto occupies the corresponding leading Lagrangian point, 60 degrees ahead of Tethys.
Four trojan moons are presently known in the Solar System. Calypso and Telesto are two of them, both orbiting as Tethys trojans at Saturn.
Calypso was officially named in 1983 after Calypso of Greek mythology. It is also designated Saturn XIV and Tethys C.