Short answers, pulled from the story.
Bonaparte took command of the Army of Italy on the 27th of March 1796. He arrived to find an army suffering from a lack of uniforms, irregular reinforcements, and widespread indiscipline, including royalist songs being sung openly among the troops.
The Army of Italy is best known as one of Napoleon Bonaparte's early commands during his Italian campaign in the French Revolutionary Wars. After Bonaparte purged disloyal officers and reformed discipline, it became, by contemporary accounts, the most Jacobin of all the French armies.
Much of the original Armée d'Italie was absorbed into the Army of Egypt. A new formation called the armée de Réserve was organized at Dijon on the 8th of March 1800 and took the name Armée d'Italie on the 23rd of June 1800 after merging with the remnants of the original force.
General Berthier held the title of Général en chef from the 2nd of April to the 23rd of June 1800, and it was under his command that the army defeated the Austrians at the Battle of Marengo on the 14th of June 1800.
Eugène de Beauharnais commanded the Armée d'Italie during the war of the Fifth Coalition in 1809. Under him, the army fought the Austrians at Sacile, Caldiero, the Piave, and Raab.
The Army of Italy relied on "war contributions" extracted from conquered lands to ease pay problems and improve resupply after its first victories in 1796. Before those victories, the army was sometimes reduced to looting to survive due to irregular supply.