Short answers, pulled from the story.
The Congress of Vienna convened between September 1814 and June 1815. Representatives from all European powers gathered in the Austrian capital during this period to discuss a new political layout for Europe.
Austrian Foreign Minister Klemens von Metternich developed the congress format as an innovative diplomatic organizational framework. Friedrich von Gentz assisted Metternich in creating this structure that brought national representatives together in one city.
Prussia added territory from smaller states including Swedish Pomerania and most of the Kingdom of Saxony. The nation received sixty percent of Saxony becoming part of new Province of Saxony from 1816 onward.
Representatives from Austria France Portugal Prussia Russia Sweden-Norway and Britain signed the document embodying separate treaties. Spain did not sign initially due to aggressive Austrian influence in northern Italy and lack of non-great power involvement but ended up signing the treaty in 1817.
Charles-Maurice de Talleyrand skillfully inserted himself into inner councils despite initial exclusion by victorious powers to control proceedings. He allied with a Committee of Eight lesser powers including Spain Sweden and Portugal before abandoning his allies once he became part of inner negotiations.