HOUSTON - Enron Corp. founder Kenneth Lay has embraced myriad roles in his life: economist, business visionary, Houston booster, philanthropist and smooth political gladhander among them. On Monday, he'll become his most important witness. "I'm looking forward to it," the 64-year-old ex-chairman said last week with the same confident smile he has displayed since his fraud and conspiracy trial began nearly three months ago. "I want to put more of the facts and the truth out about what happened at Enron." For the last two weeks, the trial's focus rested on often contentious testimony from Jeffrey Skilling, Lay's co-defendant and...