UK Stocks-Factors to watch on May 4

May 4 (Reuters) - Britain's FTSE 100 index is seen opening open 29 points higher on Friday, according to financial bookmakers. * HSBC: HSBC Holdings PLC posted on Friday an unexpected 4 percent drop in first-quarter pre-tax profit due to a surge in investments, missing estimates, and announced plans to initiate a new share buyback of up to $2 billion. * BT: BT Group Plc is set to reveal plans to cut thousands more jobs as Britain's biggest telecommunications company battles to wi