Short answers, pulled from the story.
The main conspirators included Publius Cornelius Lentulus Sura, Gaius Cornelius Cethegus, Publius Autronius Paetus, Lucius Cassius Longinus, and Gaius Manlius. These men were disreputable senators or former candidates who had been denied political advancement.
Cicero heard initial rumors from Fulvia in autumn 63 BC and received concrete evidence via letters from Marcus Licinius Crassus on the 18th or the 19th of October. The senate declared a state of emergency by the 27th of October after reports of armed men gathering near Faesulae.
Catiline joined the conspiracy because he was rejected three times for the consulship and sought to seize power through force. He mobilized men displaced by Sulla's civil war and those burdened by large debts that his putsch promised to erase.
Five conspirators including Lentulus Sura, Cethegus, Statilius, Gabinius, and Caeparius were arrested and subsequently executed without formal trial. The senate ratified Cicero's proposal to execute them immediately following a debate where Cato the Younger urged swift action.
The final battle occurred near Pistoria early in 62 BC between Catiline's remaining forces and troops led by Gaius Antonius Hybrida. Catiline himself was killed in this engagement which ended the military phase of the uprising.