Short answers, pulled from the story.
Vladimir the Great became Grand Prince of Kiev in 978 after marching on the city with a Varangian army to depose Yaropolk. He was proclaimed knyaz of all Kievan Rus' following the fratricidal war that ended when he slew Yaropolk by treachery.
Vladimir the Great adopted Byzantine Christianity in 987 after sending envoys to study Islam, Latin Christianity, Judaism, and Byzantine Christianity. He agreed to accept Christianity as his religion in exchange for a marital tie with Emperor Basil II and subsequently destroyed pagan monuments in Kiev.
Vladimir the Great was the illegitimate youngest son of Sviatoslav I and born of a bondswoman named Malusha. He took Rogneda daughter of Prince Rogvolod by force after she refused to marry him because of her mother's status, and put her parents to the sword to secure a key fortress.
Vladimir the Great died at Berestove near modern-day Kiev on the 15th of July 1015 while preparing to chastise his son Yaroslav for stopping tribute payments. His dismembered body parts were distributed among numerous sacred foundations and venerated as relics by followers of the faith he adopted.
Vladimir the Great accumulated about seven wives and eight hundred concubines during his period of pagan rule before converting to Christianity. He also had around nine daughters whose fates remain uncertain though some became princesses of Novgorod or married foreign rulers like Casimir I the Restorer.