Short answers, pulled from the story.
The Kingdom of Italy was proclaimed by the Italian Parliament on the 17th of March 1861, the date Italy now celebrates as its national unification anniversary. The process reached its formal conclusion in 1871, when Rome was officially designated the capital following its capture in 1870.
The four central figures were King Victor Emmanuel II, politician and statesman Camillo Benso Count of Cavour, general Giuseppe Garibaldi, and journalist and politician Giuseppe Mazzini. Victor Emmanuel II was given the epithet Padre della Patria, Father of the Fatherland, borrowing from the old Latin title Pater Patriae used by Roman emperors.
On the 6th of May 1860, Garibaldi sailed from Quarto near Genoa with roughly a thousand volunteers, landing near Marsala in Sicily on the 11th of May. The force grew to 4,000 men within three days and ultimately defeated the Kingdom of the Two Sicilies, with Garibaldi entering Naples by train on the 7th of September 1860, delivering the south to the new Italian kingdom.
General Raffaele Cadorna crossed the Papal frontier on the 11th of September 1870, after Napoleon III withdrew French troops protecting the pope due to the outbreak of the Franco-Prussian War. On the 20th of September 1870, after a three-hour cannonade breached the Aurelian Walls at Porta Pia, the Bersaglieri entered Rome. A plebiscite on the 2nd of October confirmed annexation.
The Carbonari were a secret political organisation formed in southern Italy early in the 19th century that filled the void left by suppressed Freemasonry after 1815. Drawing middle-class professionals and intellectuals, the group promoted Italian nationalism, opposed tyranny, and continued as a source of political agitation from 1820 until after unification. Many leaders of the unification movement were at one time members of the organisation.
Unification was structured almost entirely around Piedmontese institutions. Cavour died in June 1861 at 50, and most promises made to regional authorities were ignored. Piedmontese tax rates, laws, officials, and the Piedmontese constitution were extended across all of Italy. The first decade of the kingdom saw savage insurrections in Sicily and the Naples region, and the economic integration of the northern free-market economy with the southern state-protectionist economy caused the south's economy to collapse, giving rise to what became known as the southern question.