Zion prepares for an attack by the machines, who are boring down from the surface in an attempt to annihilate the only free humans still remaining on the planet. Although finally convinced that he is the One, Neo (Keanu Reeves) isn't sure what he is supposed to do. Consequently, he, Trinity (Carrie-Anne Moss), and Morpheus (Laurence Fishburne) again seek council from the Oracle (Gloria Foster), and the news is not good. Neo is told that he must find the Keymaker and enter the Source, the machine mainframe, and that, at some point, he's going to have to choose whether Trinity lives or dies.

The Matrix Reloaded is the second film in the Matrix trilogy, preceded by The Matrix (1999) and followed by The Matrix Revolutions (2003). Like The Matrix before it, the screenplay for Reloaded was written and directed by Andy and Lana Wachowski. So far, there have been no official novelizations.

Six months. In the interim, the surviving crew of the Nebuchadnezzar have been protecting the people of Zion and freeing other humans enslaved in the Matrix.

Yes, as Mr Smith or simply Smith. Although it seemed that Neo destroyed Agent Smith (Hugo Weaving) at the end of The Matrix, Smith has the ability to reboot himself. In Reloaded, he returns with the additional ability of being able to indeterminately replicate himself by overwriting any software hardwired-or even otherwise connected-to the Matrix. He is also "unplugged" as he puts it, no longer under control of the mainframe.

Tank (Marcus Chong) was wounded by Cypher (Joe Pantoliano) in the first film. In Reloaded, he has been replaced as the Nebuchadnezzar's Operator by Link (Harold Perrineau). When Link is talking to Zee (Nona Gaye), she says that she lost two brothers (Tank and Dozer) to the Nebuchadnezzar. It can be assumed that Tank either died of his wounds or was killed on a mission in between the films. In real life, Chong demanded a higher salary for the second movie and was let go by the producers.

That was an excerpt from The Brides of Dracula (1960).

The Twins, (Adrian Rayment) and (Neil Rayment), are leftover programs from a previous version of the Matrix. When the Architect (Helmut Bakaitis) created the first Matrix, it was an utopian society. The human psyche rejected this environment, and it crashed. The second version of the Matrix was the complete opposite of the first. (It was a dystopian society with supernatural mythological figures (including ghosts, werewolves, and vampires.) The human psyche also rejected this environment, resulting in a crash. When the third and stable version of the Matrix was created, programs from previous versions were considered obsolete, and many were purged. Some went to work for the Merovingian (Lambert Wilson), who protected them from deletion. The Twins have been variously described as ghosts, specters, or wraiths.

Bane (Ian Bliss) was a crewman on the Caduceus before his body was taken over by Smith on the night of the Zion party.

If by "saved" we mean the salvation of Zion as the Architect describes it (picking certain people to repopulate Zion), it would (by assumption) be what the Machines expected to happen. They didn't necessarily have a plan for situation otherwise, but most likely they did—with or without the guidance or consent, of Architect or of the other capitol programs. If Neo attempted to rescue Zion, he would fail ("rest assured, this will be the sixth time we have destroyed it, and we have become exceedingly efficient at it"), and the Machines would allow the Matrix to go irreversibly offline ("a cataclysmic system crash killing everyone connected"), thereby exterminating humanity altogether and threatening the Machines' continued existence (thus possibly tantamount to mutual assured destruction), but the Architect also assures Neo, "There are levels of survival we are prepared to accept."