The maximum number of Cardinal Electors allowed at any one time is 120. This is made sure by the fact that the Pope cannot elevate any more than 120 men under 80 to the Cardinalate at any one time. At the time of this writing, there are, there are 117 Cardinals eligible to vote in Conclave.

The basic process goes something like this; when the Pope dies, the Cardinal Camerlengo (or the chamberlain of the Holy Roman Church, currently Eduardo Cardinal Martinez Somalo) must verify the death, traditionally by calling the Pope three times by his name without response. The Cardinal Camerlengo must then authorize a death certificate and make the event public by notifying the Cardinal Vicar for the Diocese of Rome. The Camerlengo then seals the Pope's private apartments. He would also arrange for the "ring of the fisherman"...

He then makes preparations for the Papal funeral rites, the novemdieles, the nine days of mourning.
During the interregnum, or the time between reigns of Popes, it is the Camerlengo who is responsible for the government of the Church. He must arrange the funeral and burial of the Pope. He directs the election of a new pope, assisted by three Cardinals, elected by the College of Cardinals, with three new Cardinals elected every three days.

All of the cardinals whom the last Pope had working for him in his "cabinet" are expected to resign their position when the Pope dies. The only exceptions to this are the Cardinal Camerlengo, the Cardinal Vicar of Rome, the Major Penitentiary (James Cardinal Stafford), the Cardinal Archpriest of St. Peter's Basilica and the Vicar-General for