Hmmmm, nobody's answered so I'll try to fill in the pieces I know.

Para 1) No clue. Sorry.

Para 2) I suspect the easiest way is to remove the door panel. The speaker covers you asked about are removed by taking out the fasteners from the back of the panel. You can't pry them out from the front without breaking them. You've got to pull the panel to remove the speaker covers. Even if you could get the covers off, the speaker "box" behind the covers would preclude you from getting inside the door directly. Do a search and you'll find out how to remove the panel. Its not hard, but there are a few tricks.

Para 3) You don't need the "special tools". I've pulled my panel with two pieces of coat hanger bent in the right shape. Worked fine. Removing the center vents is a task in itself. I sure wouldn't got thru all of that to pull the cluster. Besides, once the vents are out, you'll be fighting your way past the top of the climate control plenum and its associated vacuum controls to get where you're trying to go.

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KenP

1996 S500 W140 Coupe