I do water/apple cider vinegar for a spritz. Doesn't matter a whole lot.

Cook it to 200, I do 203. It's hard to fuck up pork butt and it sounds like you're doing great so far.

If you have time, let it go. If you're short on time, wrap it in foil 3-4 hours before you want it finished.

When you pull it off, rest it for at least 30 minutes wrapped in foil.