NEW YORK - CBS on Wednesday appointed its top sports executive, Sean McManus, to replace Andrew Heyward as head of a news division still searching for Dan Rather's replacement and seeking to rebound from last year's discredited report on President Bush's military service. McManus, 50, follows in the path of the late Roone Arledge at ABC as an executive who took over a network news division while still running sports. Heyward will leave two months shy of his 10th anniversary running the legendary news division, a distant third in the ratings in both the morning and evening yet still the...