Short answers, pulled from the story.
Voltaire was a French Enlightenment writer, philosopher, satirist, and historian born Francois-Marie Arouet in Paris on the 21st of November 1694. He adopted the pen name Voltaire in 1718 following his imprisonment in the Bastille, and he is known to have used at least 178 separate pen names in his life.
Candide, ou l'Optimisme, published early in 1759, is Voltaire's best-known work. The novella satirizes Gottfried Leibniz's philosophy through the character Pangloss, who repeats that this is of necessity the best of all possible worlds. It also contains a sharp passage on slavery and ends with the conclusion that it is up to us to cultivate our garden.
Voltaire was exiled to England after a quarrel with Guy Auguste de Rohan-Chabot, whose servants beat him and whose family had him imprisoned without trial in the Bastille. He asked for exile as an alternative punishment and was escorted to Calais on the 2nd of May 1726. Britain's constitutional monarchy and its greater freedom of speech and religion deeply influenced his thinking.
No, that quotation is apocryphal. The words were written in 1906 by Evelyn Beatrice Hall, under the pseudonym S. G. Tallentyre, in her book The Friends of Voltaire, as a summary of Voltaire's attitude toward Claude Adrien Helvetius. Her first-person phrasing was mistaken for an actual quotation from Voltaire.
Voltaire campaigned to clear Jean Calas, a Huguenot merchant tortured to death in 1763 over the supposed murder of his son. Seeing it as religious persecution, Voltaire managed to overturn the conviction in 1765. He also defended other persecuted individuals, including Claude Chamont and the Comte de Lally.
Voltaire died on the 30th of May 1778, having returned to Paris that February for the first time in over 25 years to see his tragedy Irene. Denied a Christian burial in Paris, he was buried secretly in Champagne. On the 11th of July 1791 the National Assembly had his remains enshrined in the Pantheon before an estimated million people.