Putting back the cables and door handles is straight forward, I do not think you will have any issues there
No, it will interfere with the window opening at all
You should cut the mat around the door clip instead of just putting a hole, it make it easier to put the door panel back.
Also, make sure you have some extra clips, just incase you break or loose one:
Concerning the ambient light on the door panel, it wasn't easy at all, that's why I did not document it here or took any pictures.
The main issue:
I could not find +12V inside the door panel where you can tap to power the LED. The lights on the windows UP/DOWN switches are +5V, that's why I could not tap into them. So I had to route +12V, and +ILLUM signals from inside the car by going through the rubber boot connecting the door to the car chassis. There is a big connector on that rubber boot, so you have to be very careful not to break any existing wires when fishing the wires to power the LEDs from the inside of the car. Not an easy task, and takes lots of time to fish those wires (+12V and ILLUM) through.
The +ILLUM signal powers all the LED, because they only come on when the headlights come on.