1 pointYou need a wiring diagram. Almost all electrical loads go through a computer module. The aux outlets may be controlled to set the timeout, switch on with ignition etc. I doubt you will find a wire that goes from the fuse to the socket. You may need to program the module for the new outlet. Nothing is simple any more.
1 pointI said this before: the interior lights will have +12v on both terminals when they are OFF. One terminal is pulled to GND by the BCM to turn the lights on. The dimming effect happens when GND slowly increases to +12v. Some LEDs will dim, others will reach a threshold voltage and flicker then turn off. It depends on the LED driver circuit.