Mayor Seeking Major Changes at Ground Zero
Mayor Michael Bloomberg calls for removal of commercial leaseholder Larry A Silverstein from planning for redevelopment at ground zero in Lower Manhattan, and broad rethinking of plans; calls for more housing and less emphasis on building office space; is jumping into fray at fractious moment, after Gov George Pataki removed Drawing Center and International Freedom Center from cultural building and abrupt resignation of Roland Betts from Lower Manhattan Development Corp; has no power to remove Silverstein, nor can he dictate whether housing is included; Pataki aide John P Cahill dismisses Bloomberg's comments, and Silverstein calls them 'confusing,' saying administration participated at every stage of development plans; Bloomberg's remarks come at time when Democrats charge that he has not been involved enough in planning efforts, but seem to reflect public's impatience with pace of redevelopment; photo (M)

