I hope, for the missionaries' sake, they don't ever have the pleasure of meeting you. With respect to your questions, you'd probably get different answers to the first two of them, depending on the missionaries, particularly since these are scientific questions, not theological ones. For instance, If I were the missionary, my answer to question #1 would be, "About 4.5 billion years." My answer to question #2 would be, "Yes." My answer to question #3 would be, "Why shouldn't I? Do you believe all of the planets in the universe have been identified and named?" Your suggestion that they take an IQ test is insulting to say the least. Let me just tell you a little bit about the leadership of the Church of Jesus Christ of Latter-day Saints...
Among the LDS Churchs fifteen highest ranking leaders (the First Presidency and the Quorum of the Twelve Apostles") are eight men with doctorate degrees from Harvard, Yale, Purdue, and Duke. Three are lawyers, one of them a former Supreme Court Justice and law clerk to U.S. Supreme Court Chief Justice, Earl Warren, one a heart surgeon and the former president of the Society for Vascular Surgery and chairman of the Council on Cardiovascular Surgery for the American Heart Association, several who were professors at Stanford, Texas Tech and the University of Chicago, one of them being a university president. One was the former senior vice president and chief pilot of Lufthansa Airlines. One was on the staff of Adm. Hyman Rickover, developing military and private nuclear power reactors. One was the CEO of a California health care system, another the associate general counsel of what is now Bank of America in Charlotte, N.C. One was a pilot in the Pacific Theater in World War II. I suspect there isn't one in the bunch whose IQ is not significantly higher than yours.