THE INSURGENCY WASHINGTON, Dec. 2 - The expulsion of Iraqi guerrillas and foreign fighters from Falluja has provided the American military with a treasure-trove of intelligence that is giving commanders insights into the next phase of the insurgency, and helping them reshape the American counterinsurgency campaign, senior Pentagon and military officials say. Documents and computers found in Falluja are providing clues to the identity of home-grown opponents of the new Iraqi government, mostly former Baathists. The intelligence is being used to hunt those leaders and their channels of financing, as well as to detect cracks, even feuds, within the insurgency...