Hi MascaratumB, I’m sure you’re getting excited to start your mod.
For the switch, I only used the plastic holder. With the bigger switch in the holder, I had to press very hard press to get it into the tail, but that also helps keep it in place.
Yes, soldering a wire from the tab to the top of the spring will be a spring bypass, but only 1 tab should touch the side of the flashlight else it will always be on essentially bypassing the switch.
I used the insulation gasket when I got the aluminum reflector. The cheapo flashlight came with a smooth plastic reflector so it didn’t need the gasket. The gasket helps prevent a short across the LED. The rings came from the original plastic reflector which was designed to work with the original LED. I tried experimenting with the plastic reflector height here: Mod Advice For a Cheapo Flashlight, but wasn’t too successful.