SOMERSET, N.J./SAN FRANCISCO (Reuters) – As U.S. stock indexes dropped in volatile trading and oil crashed below $30 a barrel on Friday, Federal Reserve officials stuck to a well-worn script: day-to-day financial market swings do not drive monetary policy. At the same time, the chiefs of two regional Fed banks signaled they are watching inflation closely and the potential impact of falling inflation expectations on monetary policy. The influential chief of the New York Fed warned that slumping oil prices (CLc1) (LCOc1) and a strong dollar (.DXY) have raised the risk of U.S.