Ecuador's next president faces rampant drug violence and few resources to combat it / Ecuador's head of state leads in presidential election -- preliminary results / Ecuador's incumbent president and a leftist lawyer again vie for the top job in election runoff / What to know about Ecuador's presidential runoff election / Ecuador's conservative incumbent and a leftist lawyer advance to presidential runoff / Ecuador voters choose president with hopes to end violence / Ecuador votes for president, with the conservative incumbent and a leftist lawyer in the lead