Short answers, pulled from the story.
Abaris the Hyperborean was a legendary sage, healer, and priest of Apollo described in ancient Greek sources. He was the son of Seuthes and was said to have come from Hyperborea, the mythical northern land, fleeing a plague there. He was known for the gift of prophecy, Scythian dress, and a reputation for curing cities of pestilence.
According to Herodotus, Abaris traveled around the world carrying an arrow symbolizing Apollo while eating no food. Heraclides Ponticus, writing around 390-310 BC, elaborated that Abaris actually flew on the arrow. Iamblichus later described how the dart carried Abaris over rivers, lakes, marshes, and mountains, and was used to expel pestilence from Sparta and Knossos.
Plato, in the Charmides (158C), classed Abaris among the Thracian physicians who practiced medicine on the soul as well as the body through the use of incantations, the Greek term being epodai. This placed Abaris within a tradition of holistic healing considered foreign to mainstream Greek medicine.
According to Iamblichus in the Vita Pythagorica, an elderly Abaris was traveling through Italy on his way back to Hyperborea with gold he had collected to consecrate to Apollo. Upon meeting Pythagoras, Abaris immediately believed he was Apollo himself. He gave Pythagoras his magical dart, and Pythagoras responded by revealing his golden thigh as confirmation, then invited Abaris to join his community.
The Suda attributed several works to Abaris, including Scythian Oracles in dactylic hexameter, a prose theogony, a poem on the marriage of the river Hebrus, a work on purifications, and an account of Apollo's visit to the Hyperboreans. Ancient scholars regarded these texts as no more genuine than the forged letters supposedly exchanged between Abaris and the tyrant Phalaris. His fragments were collected by Felix Jacoby as FGrHist 34.
A Senior Society at Dartmouth College is named Abaris, one of eight such societies there. The band Therion wrote songs about him, including An Arrow From The Sun on Lemuria and The Wand of Abaris and The Falling Stone on Gothic Kabbalah. Peter Kingsley also made Abaris a key figure in his 2010 book A Story Waiting to Pierce You: Mongolia, Tibet and the Destiny of the Western World.