Some details are still unclear, owing to Benedict's break with the tradition that papacies end with a pope's death, so these "princes of the Church" will first hold an informal session before traditional rounds of talks begin on Monday.
No front-runner stands out among the 115 cardinal electors - those aged under 80 - due to enter the Sistine Chapel for the conclave that picks the new pope, so discreetly sizing up potential candidates will be high on the cardinals' agenda.
They will also use the general congregations, the closed-door consultations preceding a conclave, to discuss future challenges such as better Vatican management, the need for improved communication and the continuing sexual abuse crisis.
Benedict ended his difficult eight-year reign on Thursday pledging unconditional obedience to whoever succeeds him to lead the world's 1.2 billion Catholics at one of the most problematic periods in the Church's 2,000-year history.
"The discussion we have in the congregations will be most important for the intellectual preparation" for choosing a pope, said Boston's Cardinal Sean O'Malley, adding the electors were already preparing spiritually for the vote by intense prayer.
"I would imagine each of us has some kind of list of primary candidates, and others secondary," said Cardinal Francis George of Chicago at a media briefing with O'Malley and another American cardinal, Daniel DiNardo of Galveston-Houston.
MOST SECRETIVE ELECTION
Conclaves are among the world's most secretive elections, with no declared candidates, no open campaigning and electors who often do not know more than a few dozen men in the room. Electors are sworn to secrecy about the actual voting itself.
George said cardinals consulted other electors before the conclave to learn more about possible choices, asking "what do you know about this candidate?" or "what kind of person is he?"
O'Malley, at his first conclave and already being mentioned in Italian media as a potential candidate, said he had been "using the Internet a lot" to read up on other cardinals.
Conclaves traditionally begin 15 days after the seat of St. Peter, as the papal office is called, becomes vacant. But that includes time for mourning and funeral ceremonies for a dead pope, so Benedict issued a decree allowing an earlier start.