2.) I was working on the driver's side (US). Using the internal switch, move the mirror as far down as possible and as far out as possible (away from vehicle). Once you do this, you can see a plastic clip behind the mirror.
Take a small flat head screwdriver and gently pry up on the clip while you pull forward on the glass of the mirror. Then use both hands to grasp the glass and gently pull forward. Things will start to unclip and the mirror will disconnect from the housing.
Here is a pic of the back of the mirror glass:
Blue arrows are pointing to some of the retention clips.
3.) Red arrows - disconnect these electrical connections to remove the mirror glass. NOTE: it was easier to use a pair of pliers to remove the white plug.