John F. Kerry has been phoning friends at all hours and reviewing vice-presidential choices dating to 1932 as the Democratic candidate nears what many consider the biggest -- and most telling -- decision of his general-election campaign, according to Democrats inside and outside the campaign. While Kerry is tight-lipped about the pick, these Democrats said the process is revealing much about how the Massachusetts senator views his strengths, his leadership style and the role of a vice president. Kerry has privately expressed confidence that voters see him as sufficiently strong on national security, they say, but wonders whether he needs...