FOCUS ON SUSPECTS IN PAST ATTACKS
Clinton Administration officals say attacks on two US embassies in East Africa only minutes apart probably were carried out by one of a small number of sophisticated terrorist groups presumed to have attacked American installations in the past; Pres Clinton orders teams of FBI agents, medical specialists and explosives experts to scenes of bombings; Under Sec of State Thomas Pickering says it is too early to single out suspects or to speculate about why embassies in Kenya and Tanzania had been targeted; Sec of State Madeleine Albright is reported to be rushing home from Italy; senior US intelligence official, speaking on condition of anonymity, says investigators are focusing on Osama bin Laden, multimillionaire Saudi-born financier who has sworn to wage holy war on United States; Administration officials say there are also suspicions that attacks may have been carried out by Islamic Holy War group in Egypt; photos (M)