I saw that video, last I checked he hasn't released the 3d files for it (there are similar trap designs on thingaverse).

I started modeling a mini-trap when the leak first came out, but I'm not sure where it would fit nicely in such a packed playfield, or how it would even get actuated during the game?
sw_ghost-trap_(resized).jpg

I suppose you could replace the existing flat trap in the back of the machine, but it couldn't stick out too far (or have the doors flip open too much). You could tie it into the flashers, but not sure what you can do with a pulsing voltage?

I know in the main ghostbusters thread, people were talking about adding blue/red EL wire to make it look like the proton streams

ProtonBeamEgon_(resized).jpg

I would imagine any "modification" to the OEM product could void warranty, ESPECIALLY with spike system. If you put a load on the existing power supply, there's no telling what it might do to components.

I doubt that, both switches should be hooked up in parallel going to the same switch matrix (so it catches either one, but only registers one). Maybe there just wasn't enough space to stick in a 2nd one.