UPDATE 1-UK Stocks-Factors to watch on May 16

(Adds company news, futures) May 16 (Reuters) - Britain's FTSE 100 index is seen opening broadly unchanged on Tuesday, according to financial bookmakers, with futures down 0.01 percent ahead of the cash market open. * EASYJET: British budget airline easyJet posted a bigger-than-expected loss in the first half of the year, though said it still expected to meet full-year targets due to strong cost control. * PREMIER: Premier Foods reported lower sales and earnings on Tuesday, ci