Short answers, pulled from the story.
William Shakespeare drew heavily on Raphael Holinshed's The Chronicles of England, Scotlande, and Irelande published in 1587. He also incorporated elements from anonymous sources like King Leir which was published in 1605 and John Higgins' The Mirror for Magistrates from 1574.
Modern editors derive their texts from three extant publications including the 1608 quarto known as Q1 and the 1619 quarto known as Q2. The third version is the 1623 First Folio or F1 which contains around 100 lines missing from the earlier quarto editions.
Nahum Tate's 1681 adaptation titled The History of King Lear omitted the Fool entirely and introduced a happy ending where both Lear and Cordelia survive. This popular revision developed a love story between Cordelia and Edgar who never interacted in Shakespeare's original text and ended with their marriage.
Harold Bloom refers to Edmund as Shakespeare's most original character noting his pure Machiavellianism lacks Oedipal motives present in other villains like Iago. Edmund has no passions whatsoever and never loved anyone distinguishing him from all other characters created by Shakespeare.
Grigori Kozintsev's Korol Lir and Peter Brook's film starring Paul Scofield date from the early 1970s. Pauline Kael hated Brook's production suggesting an alternative title Night of the Living Dead yet Robert Hatch called it excellent filming and Vincent Canby described it as exalting with exquisite terror.