CALGARY - Two Iranian men ''capable of posing a threat to Canada'' scouted a gigantic natural gas facility on the Alberta-Saskatchewan border three months before Sept. 11, the National Post has learned. The sprawling facility, near Empress, Alta., is made up of a series of natural gas processing plants and pipelines and is the key export point for Canadian natural gas shipments to the United States. Canada supplies nearly 30% of all American gas and a disruption could shut down industry, home heating and power generation in vast portions of the United States. Information about the two men, one of...