Yes, you’d set the Focusrite as your microphone in Google Voice. It should be on the dropdown list so long as you’ve already got it set up as an audio input for Windows/MacOS. I’m sure the SM57 will work just fine, but since it’s an instrument mic you may want to get a cheap pop filter to keep the plosives at bay.
I don’t record my calls (yet), but in trying I’ve found Audacity to be tricky, at least on a Windows laptop (haven’t tried it on my Mac). I can’t have both the soundcard AND the mic as input sources - just one or the other. So I only get one side of the call.
@drwat has mentioned using OBS for recording, and @josephnormandgrinnel has elaborated on how he records here:
As for sound effects, you could add those “in post”. Just add a new audio track to the Audacity project and drop the sounds wherever you want, after the fact.
Have fun!