March 30 (Reuters) - Britain's FTSE 100 index is seen opening down 5 points on Thursday, according to financial bookmakers. * GENEL ENERGY: Genel Energy is set to lose its finance chief while still struggling to find a replacement for Chairman Tony Hayward, sources told Reuters, increasing pressure on the company after a second revision to its Kurdish oil reserves sent its shares sliding this week. * BHP BILLITON: Chile's Escondida named a new president to run a mine operate