The War Between The Street And Floor
Fall of Richard A Grasso at New York Stock Exchange, pushed by Goldman Sachs chairman Henry M Paulson Jr, and rise of Lloyd C Blankfein at Goldman discussed as emblematic of fragile state of NYSE's auction-based stock trading model; Blankfein leads group of technology-obsessed executives who have used electronic trading platforms to make bond trading major profit center at Goldman as stock trading increasingly became low-margin commodity business; Goldman reportedly weighs getting rid of its costly research department; photos (M)