Okay I am going to go ahead and give this a try here in a minute.
When you say to briefly test the switch before installing it, are you referring to testing the switch out with a screwdriver, and turning it? What should I be careful about, precisely?
Edit: Okay I gave it a try and it seems to all check out, and I can hear the fuel pump turning on, as before. However, she is still not turning over. I think after all this trial and error, I believe this piece:
Is what's causing it to not run? Unfortunately the little plastic piece broke and the little spring could no longer fit, so I would need to acqure a new set somewhere.