King Fahd's official visit to the United States, which begins with his arrival in Washington next week, has already aroused intense speculation, debate and comment in America's political capital. Presidential spokesman Larry Speakes said, in a statement of them blindingly obvious, "We regard the King as an important friend in the Middle East. We have a continuing interest in Saudi Arabia." He said that Secretary of State Shultz had specifically recommended to President Reagan that the Saudi monarch should be one of the first leaders the President should meet early in his second term.