Correct, T-15 torx screw at the rear of the front door holds the lower piece on the front door; T-15 at the front of the rear doors holds the lower piece of the rear doors on. The small piece up by the mirror is actually part of the upper, which is why I replaced my front uppers. The door panels need to come off to be able to change the front uppers and rear vertical pieces, the cover panel hides some hardware which is of course covered by the door panel.
The easiest way to do the rear vertical is to pull the door panel, then the inside trim panel (this has one of those clips that always breaks near the rear curve of the window). With the inner trim piece removed, there is a black hole plug near the top back of the window, and another T-15 that secures the vertical window trim. Now pull the outside lower window trim, which is also clipped to vertical piece. The vertical piece is now only held on by 2 small white push in clips, pop them out then gently pull down a bit to free the upper trim enough that you can pull the vertical piece out. Install is just the reverse, when you go to put the inner trim back on, make sure the window is down, as the trim piece has an edge that hooks onto the metal near the window and then wrap it around, and put the weather seal back on top of the trim.
The front door inner trim piece needs to be removed to do the upper trim, which is hiding 3 T-15 torx and 2 rivets. Steps for the uppers are fairly close to the rears, remove the door panel, then the inside trim piece (the clip on this one is near the front of the door, bottom 1/3 of the window), then remove the outside lower window trim, then the rear vertical, then the triangle piece, then you can remove the upper. The rear vertical is held on with a T-15 and 2 white clips like the rear, only trick is that is wraps around the back of the door. At the front of the door are 2 black hole plugs, with T-15 underneath, these hold the triangle piece on, which also has a small white clip. The upper trim is held on by 2 rivets and 2 small white clips.