* U.S. team includes FAA, NTSB and Boeing * Japanese battery maker also helping in investigation * Separate 787 fuel leak due to valve-related malfunction * Initial investigation by midday Saturday - source By Antoni Slodkowski TAKAMATSU, Japan, Jan 18 (Reuters) - A team of experts from U.S. aviation authorities and Boeing Co arrived in Japan on Friday to inspect a 787 Dreamliner passenger jet that made an emergency landing on a domestic All Nippon Airways Co flight earlie