Is your seat lopsided at all?? Because one of the lifter arms could possibly be broken at the weld.
It could actually be your seat frame which is unfortunate because if that's warped it's an expensive replacement.
Here is the FSM if you're a do -it-yourselfer
http://www.nicoclub.com/FSM/G35/
You could try to loosen the mounting bolts on the of the seat rack and take a pry bar and push the mounting bracket in and tighten the bolts back down. Essentially putting pressure on the rack mounts. It can reduce or elimnates the noise.
The creak could be coming from the left rear (near the door) seat support pivot point. This fix involves adjusting seat support by the two nuts and cross brace bolt.
Here is something you can try
Trim piece removal1) remove the two screws from the front of the seat trim piece2) remove the plastic clip (black) from the lower rear of the seat trim piece 3) remove seat trim piece by pulling it towards you and then back and up. There is a metal piece that fits into a slot in the seat trim piece which necessitates the need to rotate the piece backwardsa bit. 4) remove seat control units from the trim piece by simply unclipping them
Seat support5) take a 12mm socket or 12mm wrench and loosen (no need to remove) the bolt securing the cross brace to the left rear seat support. 6) take a 12mm socket or 12mm wrench and loosen (no need to remove) the nut securing the front left rear seat support to the seat frame.7) take a 14mm socket or 14mm wrench and loosen the nut securing the back left rear seat support to the seat frame.
Adjustment8) push the left rear seat support inwards slightly (maybe 1/8") and then with your hand keeping the support in position, lock down the front and back 12 and 14mm nuts.
Reinstall everything in reverse order and see if the seat creaks. If that didn't solve the problem entirely, continue to shift the seat support around until the noise dissappears.
As for your charger outlet, it does souns like a fuse. Do you have a continuity tester??
Hope that helps!