I solved the button and lever puzzles in the Walls of Mist the same way you did, brute force and ignorance. If there were any clues or short cuts, I never found them. That was one of the things I found very useful in MM3, plenty of clues are given but only provided that you find them! You need to turn to look at every wall in every corridor when you are exploring the dungeons, so don't side-step, even if it's obviously quicker. You need to turn to face a wall before you can read what is on it, you cannot see any writing on a wall by walking along parallel to it. And if you do play MM3 at any time, be warned – occasionally, clues found in one dungeon sometimes apply to puzzles in a different (but related) one
Yes, the Queens of the Dead are nasty. you'll find a lot of them in The Pit . . .