Be mindful that there's much, much, more to the story than credits pages in guides and major threads. There are lots of threads on modretro that help fill in the story, but the forums are down right now, so I can't pull them up. Here's a BitBuilt thread that has some Wii history.
Check each voltage rail to gnd and make sure your resistance is abnormally low. Once that's done, sand it with some high grit and you should be good to go
This is misleading.
The sensor bar is powered by a 12v pwm signal. If you are referring to "powering a sensor bar off USB" only later versions with less LEDs can do that.
The sensor bar doesn't send any data, it's just a bunch of LEDs the Wii remote sees. You can use any IR LEDs you want, with...
If you are really struggling to get them off, I think you would be better off trying to get a hold of an RVK board from a family edition Wii. The board is essentially the exact same, but it just doesn't have any GameCube ports soldered onto the pads