By MELODY McDONALD MILFORD — Off a muddy road in rural Hill County, in a nondescript tan mobile home, Hosam "Sam" Smadi made his final plans to bring down a Dallas skyscraper, authorities say.Federal officials learned about the well-hidden mobile home after arresting the 19-year-old Jordanian on Sept. 24. Smadi gave the FBI written consent to search the residence, where he moved Sept.