Short answers, pulled from the story.
Marcus Furius Camillus appears in the Etruscan François Tomb built near Vulci around 350 BC. One painting there shows a figure named Gneve Tarchunies Rumach being killed by Marce Camitlnas. Scholars debate whether this Marce refers to the Roman statesman or someone else entirely.
Livy claims Camillus served as dictator to complete a ten-year siege against Veii ending in 396 BC. The narrative describes Alban Lake rising supernaturally after a prophecy found in the Books of Fate. Archaeological remains near Veii include blocked drainage tunnels dating to the fifth century BC.
Greek sources from the fourth century BC describe Gauls crossing the Apennines into northern Etruria around 387 BC. They defeated Rome's army at the Battle of the Allia and entered the city to sack it. The Gauls occupied the city for about seven months before leaving voluntarily to face an invasion by Veneti.
Camillus is alleged to have been elected dictator in 368 BC to obstruct efforts by Gaius Licinius Stolo and Lucius Sextius Lateranus. He later reconciled patricians and plebeians with a proposal appointing a patrician-only praetor. This compromise allowed plebeians to hold consulship while maintaining curule aediles positions.
Modern historians view the traditional account of Camillus as heavily constructed based on annalistic traditions that no longer exist in full. Mary Beard described Camillus as possibly not much less fictional than Romulus herself. Thomas Mommsen labeled the entire legend the most dishonest of all Roman stories.