* FTSEurofirst 300 up 1 pct, Euro STOXX 50 up 1.5 pct * FTSEurofirst 300 set to post 9th straight weekly gain * Drop in volatility signals surge in risk appetite * Bank index up 12 pct on the 'Draghi effect' * Siemens soars after starting stock buyback programme By Blaise Robinson PARIS, Aug 3 (Reuters) - European stocks rose on Friday morning, erasing most of the previous day's pull-back and resuming a week-long rally as investors judged the European Central Bank remains committed to bold action to fight the debt crisis.