Short answers, pulled from the story.
Bohdan Khmelnytsky's father Mykhailo died on the 17th of September 1620 during the Battle of Cecora. Young Bohdan stood among captured soldiers as Ottoman forces took him prisoner following this event.
One theory credits Krzysztof Zbaraski who paid 30,000 thalers for prisoners in 1622 to ransom Khmelnytsky back to Ukraine. Sources vary on how he escaped or was ransomed but he returned to Subotiv to resume control of his father's estate.
Eviction succeeded by early 1647 forcing Khmelnytsky to move with his large family to a relative's house in Chyhyryn after Daniel Czapliński raided his property twice. Unable to regain land or compensation Khmelnytsky traveled through autumn 1647 consulting Cossack leaders before being arrested by local authorities which preceded his election as hetman at the end of January 1648.
Bohdan Khmelnytsky suffered cerebral hemorrhage on the 22nd of July 1657 after an audience with Kiev Colonel Zhdanovich becoming paralyzed. He died less than a week later at 5 a.m. on the 27th of July 1657.
Between 1648 and 1656 estimated deaths range from 18,000 to 100,000 Jews including starvation and disease victims sold as slaves to Tatars. Contemporary witnesses claimed members of Cossack starshyna directly oversaw this process acting on hetman orders.