Short answers, pulled from the story.
Marmont negotiated a secret agreement with the Allies in 1814 and surrendered his forces near Paris, effectively ending Napoleon's campaign. This act led to the French verb "raguser," derived from his title Duke of Ragusa, entering common speech as a word for betrayal. He was later accused of a second betrayal when his troops failed to suppress the July Revolution of 1830.
Marmont commanded the French army in northern Spain at Salamanca in 1812. Wellington ordered a cavalry charge against Marmont's unsuspecting left flank, delivering a decisive defeat. Marmont was struck by shrapnel early in the battle, wounded gravely in his right arm and side, and command passed to Bertrand Clauzel.
Marmont was made a Marshal of the Empire by Napoleon following the Battle of Wagram, fought on the 5th and the 6th of July 1809. He was one of three marshals created after that battle. Napoleon privately told him that he had not done quite enough to fully justify the appointment.
Marmont accompanied King Charles X into exile after the July Revolution of 1830 and never returned to France. He settled mainly in Vienna, where the Austrian government received him warmly. He died in Venice on the 22nd of March 1852, the last living Napoleonic marshal.
Marmont served as military and civil governor of Dalmatia for roughly five years following his posting there around 1805. He oversaw major public works that outlasted his rule and earned a favorable reputation among the local population. In 1808 he was awarded the title Duke of Ragusa in recognition of his tenure there.
Marmont published Voyage en Hongrie in four volumes in 1837 and Voyage en Sicile in 1838. His Esprit des institutions militaires appeared in 1845. His Mémoires, in eight volumes, were published after his death in 1856 and are regarded as a valuable source for the military history of the Napoleonic era.