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PS For future reference, does this sort of exposed PCB trace (pad?) used for electrical connection take solder well?

I can’t tell if you have gold plate or just raw copper (probably gold. But in either case, yes, it is solderable. You can think a little bit about how they manufacture the boards. First the print on the green solder resist, then they dunk it into an electroplating bath for a gold finish, or a dunk it in solder for HASL. It would be a lot of trouble to go through (=$$$) to individually mask off that part of the board for some special process.

Open it up!

They put a regular old switch inside a fancy box, but you’ll be able to read the part number once you see the actual switch.

Unless you’ve managed to get a switch made out of superconducting material and you’re working inside a liquid helium bath, everything has resistance :)

You’ll have a bad time trying to measure such low resistances, so usually you can look at the datasheet for the switch you’re using or for a similar switch if you need a ballpark number. You’ll see an on-resistance, and a max current (since there will be arcing when you open the switch).

If you do want to measure the low resistance, you’ll need dedicated meter with a kelvin connection.