Which ruthless Russian ruled as tsar from 1547 to 1584?

Which name belongs to both a legendary city of gold and a Cadillac model discontinued in 2002? A leghorn is a breed of which farm bird? A lepidopterist studies which insects? Which Leslie Nielsen film comedy series was based on the TV show "Police Squad!"? Complete the title of Marcus Pfister's picture book about sharing: "The Rainbow ___". An orange letter C with white trim is the logo of which NFL team? Which word sounds like a letter of the alphabet and means a former spouse? Which word means both a level of stability and an elevated flat surface?