1. As I said before,
You realize that just typing a few words into google/bing/whateveryoumightuse would get you the answer, right?
2. There are no worlds in any DKC games that are specifically labeled as "Mystic". However...
3. If you mean by secret worlds after the game, then DKC 2 has the Lost World and DKC3 has Kremetoa. Both have secret/optional final bosses that require 100% completion to beat.
Or maybe I am falling for flame bait. Any thoughts, Qyzbud?