A racially charged controversy, ahead of the Hoover High School football team's season-opener Saturday.  An anonymous letter sent to the head coach of the visiting team -- Florida's Miami Central -- contains racial slurs and obscenities, and declares Hoover is #1.  The letter also hurls racial insults at Miami Central's fans.  The Hoover school system released a statement extending a warm welcome to Miami Central.  The statement also assures Miami Central's players, coaches, and fans that the comments in that letter are not at all representative of Hoover.  Police are investigating.  USA Today ranks both teams in the top 10 nationally, drawing ESPN coverage of the game.