I'll reply in i different order so that there is a continuity of the steps.
F - You do not need to remove the door. You need to remove the trim (the panel). Inside the door you'll need to find the 2 wires you need. Like i said before i suggest you also pull the connector (the big black plastic junction) that is tightly attached to the side of the door. There you can test you LED using different pins until you find the two ones that light up your LED. Once you find these two pins trace the wires connected to these two pins in order not to cut (or strip) the wrong ones.
E - Originally the system consists of 3 LEDs in each door. I only installed two. door pocket and the one under top trim in the space/track provided. I did NOT install the one in the interior door open handle. This latter one needs other parts (extra plastic cover with hole provided and a small fiber optic plus it's LED) i did not have and i decided to skip it. This is another reason why i came cheaper with the parts compared to what your dealer charged you.
D - You are right. But I was not comfortable with cutting so many wires. So i decided to cut only for rear doors instead for front ones as well. And this is the way i was advised by another retrofitter and i did not fell like improving the steps
. Plus ... the routing from back to front is not that difficult. Another thing...If you decide to cut wires in all the doors individually keep in mind that i didn't look for power in the front doors (since i routed the power from the aft doors) so there is a small possibility that there is no power at all inside front doors. You can try to find it the way i told you. Remove the connector and test all the pins inside it until you're sure there is power as well over there.
C - Not really sure. This way (the power from this two wires) was the only one i could find over the internet , forums , discussions after months of searching. The colors are important (polarity). I remember that i had to mark my white wires in order to know where should it go. It is better to use a pair o two different color wires unlike my option with 2 identical white wires. It will help you. It's a good idea.
A and B are also correct with the following mentioning: The 2 wires that gives you power are inside the door. The LEDs are mounted on the door panel. Betwen these two places there is a glass window that goes up and down ( like a guillotine ). The place you cut and then trace the wires twds your LEDs is very important. Also please use a lot of duct tape to glue the wires firmly on their way. That place you chose to cut (expose the inner wire) will not be too comfortable. Also you need to trace the wires towards you LEDs in such way that you window when will be opened will not cut or break everything when it goes down
. This is what happened to me once
). That is why i chose to connect only one set of wires inside the door (to be easier to route it towards the door panel). And when i had the set of two wires on the door panel i made this one into 3 separate sets that will power all your LED's. I suppose there is no harm in connecting all 3 sets to the place you cut or expose. But then you have plenty wires to route nicely inside the door so that they will not create any other problems.
Is it clear now?