It’s addition-by-subtraction time in Toronto as the mammoth musical theater version of “The Lord of the Rings” works on problems that caused the planned 3 1/2-hour show to run nearly five hours in its first preview. That’s what previews are for, and playgoers who have seen early performances are reporting back favorably. “There’s an absolutely fantastic 3 1/2 -hour show in there somewhere,” says Derrick Chua, 39, a Toronto attorney who attended the very first preview, Feb. 4, at the Princess of Wales Theatre. Chua had no illusions that he’d be seeing a finished product. [More]