Short answers, pulled from the story.
Israel ben Eliezer, known as the Baal Shem Tov, moved to the town of Medzhybizh in Podolia during the 1740s. He worked as a folk healer and mystic before gathering disciples who spread his teachings across Eastern Europe by the time of his death around 1760.
Hasidic thought centers on the phrase no site is devoid of Him from Tikunei haZohar which suggests God contracts his omnipresence to create space for free will. Followers believe matter contains hidden divine sparks that must be elevated back to their source through worship via corporeality.
Each Hasidic sect operates as an independent court led by a hereditary Rebbe who serves as both spiritual guide and administrative head. These courts maintain linked synagogues called shtiebels where followers submit written petitions known as kvitel for assistance.
Married men wear fur headdresses like the shtreimel common among Galician and Hungarian sects while unmarried sons don kolpik hats on Sabbath. Women follow tznius principles with long skirts covering legs past elbows and use wigs called sheytel or scarves for head coverings.
The ongoing Satmar succession dispute began in 2006 between brothers Aaron Teitelbaum and Zalman Leib Teitelbaum leading to mass riots. This conflict created splits such as the Bobov-45 faction formed after 2005 and resulted in communities becoming extinct during the Holocaust including Aleksander which numbered tens of thousands in 1939.
A 2016 study located 129,211 Hasidic households worldwide representing about five percent of total Jewish population. Sixty-two thousand resided in Israel while fifty-three thousand lived in the United States with large concentrations in Brooklyn neighborhoods including Borough Park Williamsburg and Crown Heights.