Short answers, pulled from the story.
Loki has five children named in the sources. By the jötunn Angrboða he fathered Hel, the wolf Fenrir, and the world serpent Jörmungandr. By his wife Sigyn he has two sons, Narfi or Nari and Váli. He also gave birth to the eight-legged horse Sleipnir after being impregnated in the form of a mare by the stallion Svaðilfari.
The Snaptun Stone is a semi-circular soapstone hearth stone discovered in 1950 on a beach near Snaptun, Denmark. Carved around the year 1000 CE, it depicts a mustachioed face with scarred lips, identified as Loki because of a story about his lips being sewn shut. It is now housed at the Moesgård Museum near Aarhus, Denmark.
Lokasenna, meaning "Loki's Flyting", is a poem from the Poetic Edda in which Loki systematically insults nearly every god and goddess at a feast hosted by the sea figure Ægir. After killing the servant Fimafeng, Loki is chased out but returns to accuse deities including Bragi, Iðunn, Frigg, Freyja, Odin, and others of cowardice or sexual misconduct. Only Thor's arrival with his hammer Mjöllnir ends the contest.
Loki is bound as punishment for engineering the death of Baldr, the beloved god. Odin's son Váli was specifically fathered to carry out the binding, and Loki is tied with the entrails of his own son Nari. The goddess Skaði places a venomous serpent above him so that venom drips onto his face; his wife Sigyn holds a basin to catch the poison, but when she empties it the dripping venom causes Loki to writhe and, according to the myth, produces earthquakes.
The most linguistically supported origin of the name Loki traces to the Germanic root luk-, associated with loops, knots, hooks, and locks rather than to the Old Norse word for flame. Later Scandinavian variants of the name correspond to words for cobwebs and spiders, consistent with a meaning of "tangler" or maker of knots. Loki also carries the byname Loptr, derived from Old Norse lopt meaning "air".
At Ragnarök, Loki breaks free from his bonds and fights alongside the forces of the jötnar against the gods. His children play key roles in the destruction of nearly all humanity during the events. Loki and the god Heimdallr are specifically prophesied to kill one another. The völva in Baldrs draumar states that no one will visit until "Loki is loose, escaped from his bonds" and Ragnarök has begun.