Short answers, pulled from the story.
The Austrian Empire began on the 11th of August 1804 when Francis II became Francis I of Austria. This new title unified all Habsburg possessions under one central government while remaining part of the Holy Roman Empire until its dissolution in 1806.
Klemens von Metternich controlled Habsburg monarchy foreign policy from 1809 to 1848 as Foreign Minister and Chancellor of State. He served as chief architect of the Congress of Vienna in 1815 where Austria gained new territories and maintained international political equilibrium through alliances with Britain, Prussia, and Russia.
Significant lasting reforms included the abolition of serfdom and cancellation of censorship following the liberal Revolutions of 1848. Ferdinand I of Austria promised to implement a constitution throughout the whole Empire despite nationalist revolts being forcibly crushed in north Italy and German states.
Baron Alexander von Bach centralized administrative authority for the Austrian Empire while endorsing reactionary policies that reduced freedom of the press. Public trials were abandoned under his administration which later represented the Absolutist party and gave the Roman Catholic Church control over education and family life via the concordat of August 1855.
The Austrian Empire ended on the 6th of December 1867 when it transformed into the Austro-Hungarian Empire following the Austro-Prussian War of 1866. The Treaty of Pressburg signed on the 26th of December 1805 had previously forced Austria to cede large territories to Napoleon's allies but the final dissolution occurred after military defeats at Marengo, Ulm, Austerlitz, and Wagram.