Short answers, pulled from the story.
Nero died on the 9th of June AD 68, taking his own life with the help of his private secretary Epaphroditus at a villa four miles outside Rome. His final words were "Too late! This is fidelity!" He had fled there after the Senate declared him a public enemy and the Praetorian Guard abandoned him.
The question remains unresolved. Tacitus, who is the most detailed ancient source, found that Nero was in Antium when the fire began and returned to Rome to organize relief. Suetonius and Cassius Dio suggest Nero started the fire to clear land for his planned palace, the Domus Aurea. Modern historians note that the merchant shops and timber circus seating where the fire began were genuinely fire-prone.
Agrippina the Younger was the great-granddaughter of the emperor Augustus and, from AD 49, the wife of Emperor Claudius and mother of Nero. Nero had her killed in AD 59; according to Suetonius, he arranged a fake shipwreck, and when she survived by swimming ashore, his freedman Anicetus had her executed and reported her death as a suicide.
The Nero Redivivus legend was a widespread belief, especially in the eastern provinces, that Nero had not truly died and would return. At least three impostors led rebellions in his name after AD 68. Augustine of Hippo was still writing about the belief in AD 422, and some Christian writers identified Nero with the figure of the Antichrist.
Nero had the Olympic Games postponed by a year so he could compete, and arranged for artistic competitions to be added alongside the athletic events. He entered every contest and was declared the winner of each, including a ten-horse chariot race in which he was thrown from the chariot and did not finish. After his death, his name was removed from the list of Olympic winners.
No historical sources contemporary with Nero's reign survived. The main accounts by Tacitus, Suetonius, and Cassius Dio were written at least fifty years after his death, with Cassius Dio writing over a hundred and fifty years later. The historian Josephus warned in the first century that earlier writers had distorted the record out of both favoritism and hatred. Modern historians also note that these sources were all members of the upper classes, the group most resentful of Nero's populist spending and public performances.