The First and Second Knights of the Grail are roles in which 1882 Wagner opera?

What does the "D" stand for in FDIC, the U.S. agency that protects bank customers' money? The Dalai Lama's former residence, the Potala Palace, overlooks which city? The famous definition of golf attributed to Mark Twain calls it "a good" what "spoiled"? The documentary "Chris & Don: A Love Story" is about painter Don Bachardy and which author of "Goodbye to Berlin"? The first four letters of "xylophone" come from the Greek word for which material, used for its sounding bars? The first entry in Reader's Digest's "Who's Who in the Bible" is which older brother of Moses? The Goliath bird-eater, whose leg span can reach about 11 inches, is a species of which spider? The Grand Nagus is the supreme leader of commerce for which Star Trek race, famous for its 285 Rules of Acquisition?