UPDATE 1-UK Stocks-Factors to watch on April 13

(Adds company news item, futures) April 13 (Reuters) - Britain's FTSE 100 index is seen opening 8 points lower at 7,250 on Friday, according to financial bookmakers, with futures flat ahead of the cash market open. * LSE: London Stock Exchange Group said it appointed Goldman Sachs' David Schwimmer as chief executive officer effective August 1. * ROLLS-ROYCE: Britain's Rolls-Royce said on Friday it would step up the number of