This looks very much like the rear end of set 8669 Fire Spinner 360:
Only differences being that the pieces are counterfeit and the red on the stickers has been replaced with green. This is therefore, presumably, from a clone-brand version of this set.
I have also little soldering experience, but I managed to create custom extension cables:
First: open the cover with a small screw driver:
Remove the PCB by lifting the small notch to open the light block
Then you drill a small hole into the opposite side of the metal plates, insert a small 2-wire cable (~0,25mm) and solder it to the PCB.
The outer ring is ...
I can't speak for other brands, but I'm sure that there is no such LEGO element.
This would be a plate, but the Bricklink category has nothing exactly like this design.
The closest would be the Plate 2 x 2 Corner or Plate 3 x 3 Cross, but the first requires an additional plate, which could prove unfeasible due to the missing structural bonds, and the latter ...
Most of them are safe, because they are made mainly out of abs plastic, but with Lego, you will be getting higher quality pieces, and you know you will always be getting the best pieces, because of quality control. From my past experience, china bricks seem fine safety wise, but I have noticed significant differences on how well the gears work, and how easy ...