Campaigns Set a Brisk, Focused TV Pace
Tone of advertising in presidential campaign is becoming noticeably more confrontational, on issues if not personalities, as strategists concentrate on states they believe are up for grabs as campaign winds down; Republicans and Democrats spent total of $18.5 million on television, evenly split between parties, in last week of September and first week of October on six highly contested states: Florida, Michigan, Missouri, Ohio, Pennsylvania and Wisconsin; Republicans are also spending in California, Minnesota and West Virginia--states thought to be long shots for Bush; Democrats are fashioning television and radio attack ads in Florida, Washington State, West Virginia and Iowa; photos (M)