Short answers, pulled from the story.
Oliver Cromwell was born on the 25th of April 1599 in Huntingdon to Robert Cromwell and Elizabeth Steward. His family estate derived from his great-great-grandfather Morgan ap William, a brewer from Glamorgan who settled at Putney.
Cromwell joined the Parliamentarian army when the First English Civil War began in August 1642 and rose to lieutenant general of horse by July 1644. He led successful actions including the Battle of Marston Moor and the decisive victory at Naseby in June 1645 which smashed the King's major army.
At the Siege of Drogheda in September 1649 his troops killed nearly 3,500 people after the town's capture. This included around 2,700 Royalist soldiers and all men carrying arms including civilians prisoners and Roman Catholic priests.
Charles I was executed on the 30th of January 1649 and Oliver Cromwell was the third person to sign the death warrant. None of the officers wanted to sign the order for the actual beheading so Cromwell seized a pen and scribbled out the order handing it to Colonel Hacker who signed it.
He was sworn as Lord Protector on the 16th of December wearing plain black clothing rather than any monarchical regalia. As Lord Protector he was paid £100,000 a year.
Cromwells body was exhumed from Westminster Abbey on the 30th of January 1661 the 12th anniversary of the execution of Charles I. His body was hanged in chains at Tyburn London then thrown into a pit before his head was cut off and displayed on the roof of Westminster Hall until at least 1684.