Some Answers to Your Questions
Who's in charge now that the Pope is dead? "It is the College of Cardinals, therefore, which remains in charge during the Interregnum. The Camerlengo and the other officials of the Apostolic Camera oversee the dicasteries and report daily to the College, which makes any decisions."
Who belongs to the college of Cardinals? There 183 Cardinals, 117 of whom are eligible to vote for a new Pope. Only Cardinals under the age of 80 are allowed to vote; they're called Cardinal Electors.
John Paul II was the 264th Pope. You know you're curious about who the rest of them were...