In his first public comments on the crash of EgyptAir Flight 990, the director of the F.B.I., Louis J. Freeh, said today that the Egyptian authorities were cooperating with the inquiry into the cause of the crash and would investigate a list of leads at the request of American law-enforcement officials. Mr. Freeh, speaking with reporters at the headquarters of the Federal Bureau of Investigation, said the authorities in Cairo were assisting American investigators even though Egyptian officials have dismissed the principal American theory that a reserve pilot might have deliberately brought down the airliner. In a separate development, aviation...