* HK->Shanghai Connect daily quota used -1.7%, Shanghai->HK daily quota used 2.5% * HSI -0.7%, HSCE -0.4%, CSI300 -0.9%* FTSE China A50 -1.2% BEIJING/SHANGHAI, March 31 (Reuters) - Hong Kong shares fell on Wednesday, marking their first monthly drop in six, as a slew of weak earnings results a