Peacetime Recruits Getting Ready for War's Perils
Thousands of young American soldiers who entered military in time of prolonged peace and prosperity face prospect of going to war; at military bases across country, looming possibility of being sent overseas is foremost in their thinking; many are barely out of high school, and thought joining armed forces was way to learn trade and help support families; many new soldiers across country say that while they may not have counted on having to hunt down terrorists, especially so soon in their careers, they are quickly coming to terms with their military responsibilities; photo (M)