Unlock All Chapters: Go to the "New Game" screen and press Up, Down, Up, Down, Left, Right, Right, Y, X, X
Disarm Weapons: All weapon classes have five disarm motions: B, Up or B, Left or B, Right or B, Down or B. The only exception is with the shotgun which uses B, or B, Up
NOTE: Disable the Random Disarm Option before attempting.