Short answers, pulled from the story.
United Russia emerged as a political bloc in the autumn of 1999 three months before the State Duma elections. Boris Berezovsky is identified by Tatyana Yumasheva as one of the founders, while Kremlin insiders created the group to counter the Fatherland All Russia bloc.
United Russia received 64.20% of the votes in the 2007 parliamentary elections according to official data from the Central Election Commission of Russia. This result allowed the party to secure 315 seats and obtain a constitutional majority in the State Duma.
Vladimir Putin operates as the de facto leader of United Russia even though he declared that accepting the nomination did not mean he would become a member. He headed the federal list for the 2007 election and served as party leader starting on the 7th of May 2008 when Boris Gryzlov was replaced.
In 2015 United Russia changed its ideology to liberal conservatism which is described as right-leaning centrism. The shift occurred due to the economic crisis in Russia at that time after previously proclaiming Russian conservatism as its official ideology in 2009.
There are 82,631 primary and 2,595 local branches of United Russia throughout all subjects of the Russian Federation. Regional branches exist in every region with the vast majority of governors being members of the party since April 2006.