Short answers, pulled from the story.
Julius Caesar is believed to have been written and first performed in 1599. Thomas Platter the Younger recorded seeing a tragedy about Caesar at a Bankside theatre on the 21st of September 1599, and the play does not appear in Francis Meres's 1598 list of Shakespeare's works.
Most critics regard Brutus, not Caesar, as the tragic hero of the play. Although the play bears Caesar's name, it focuses on Brutus's moral and political dilemmas, and scholar Joseph W. Houppert argues that Brutus is the driving force of the drama.
In Shakespeare's play, Caesar's last words are "Et tu, Brute?" followed by "Then fall, Caesar!" The phrase "Et tu, Brute?" was not invented by Shakespeare; it appeared in earlier Elizabethan works and was conventional by 1599. Historically, Plutarch and Suetonius both recorded that the real Caesar said nothing.
Shakespeare compressed the timeline significantly, placing events that historically unfolded over weeks into a single day. He also moved the assassination from the Curia of Pompey to Capitoline Hill, combined two Battles of Philippi that were separated by a twenty-day interval, and shifted Caesar's triumph to coincide with the feast of Lupercalia.
Orson Welles staged Julius Caesar at the Mercury Theatre in New York City in November 1937, dressing his cast in uniforms reminiscent of Fascist Italy and Nazi Germany to draw a direct analogy between Caesar and Benito Mussolini. The production ran for 157 performances and received a rave review from Time magazine.
Several lines from the play have had wide cultural reach. "The fault, dear Brutus, is not in our stars, but in ourselves" gave its name to John Green's novel The Fault in Our Stars and was quoted by Edward R. Murrow in his 1954 broadcast on Senator Joseph McCarthy. "The evil that men do lives after them" supplied the name of an Iron Maiden song. "There is a tide in the affairs of men" is quoted at the close of the Star Trek: Picard finale.