Short answers, pulled from the story.
The Orphic Hymns are a collection of eighty-seven brief ancient Greek hymns addressed to various deities, attributed in antiquity to the mythical poet Orpheus. A proem precedes the collection, in which Orpheus addresses the poet Musaeus and calls on around seventy deities to attend a rite.
The identity of the poet is unknown, though most scholars agree the Orphic Hymns were the work of a single author. They were most likely composed in Asia Minor around the 2nd or 3rd centuries AD, with estimates ranging more broadly between the 2nd century BC and the 5th century AD.
Dionysus is given the greatest prominence in the Orphic Hymns, receiving eight separate hymns, more than any other deity, and being mentioned in twenty-two of the eighty-seven hymns. He was probably the central god of the cult that used the collection in ritual.
The Orphic Hymns were used in rites by a religious cult community in Asia Minor that performed initiations into mysteries. The ceremony was the telete, an initiation rite that appears to have taken place at night, during which a specified offering such as frankincense or myrrh was probably burned as each hymn was recited.
The first printed edition of the Orphic Hymns was produced in Florence in 1500 by Filippo Giunta. The earliest codex containing the Hymns to reach Western Europe was brought from Constantinople to Venice by Giovanni Aurispa in 1423.
The Orphic Hymns are attributed to Orpheus through their title and the proem's address to Musaeus, and the collection is written in the first-person voice of Orpheus. In antiquity, ascribing a work to Orpheus lent it special authority and placed it even earlier than Homer, whom Orpheus was believed to have preceded.
The Orphic Hymns follow a sequence running from birth to death, opening with a goddess of birth, Prothyraia, and ending with Thanatos, or Death. Each individual hymn has three internal parts: the invocation, the development built largely from strings of epithets, and the request.