What are the standard Dice Pool penalties for lighting conditions? There's descriptions and listed bonuses for Stealth but nothing for other action rolls that involve sighting.

I would guess:
Shadowy: -1d (Partially concealed)
Darkness: -4d (Representing total concealment)

I think you have the right of it by the RAW. I actually went back to 1st Ed, as those modifiers for lighting are slightly more granular and make more sense to me. You can also use them alongside the concealment modifiers (not combined , though) from 2nd Ed just fine.