Stuffing

I think it depends a lot on why you are stuffing. To dain, I'd say ease off on how much, but keep up the frequency. To feel stuffed and/or see your belly swollen up I'd ease back a bit on the quantity of food, and how often-- but top off the food with more to drink. Can finish swelling up on liquid, but it absorbs faster, so doesn't disrupt the rest of your digestive track as much. At least in my experience.

A day is usually enough for me. On that day I'll usually eat a little just to keep my stomach from growling. Ideally you'll want 48+ hours of nothing but liquid to completely flush out your system for a hardcore stuffing. That's what professional eaters do anyway.

When you say your stomach was upset, what kind of pain was it? I've noticed that if I take an extended break of months from stuffing when I start it again my stomach will feel sore in the same way a muscle will after you train it for the first time in a while. If you're feeling stick you might want to try taking a longer break period between to get used to it.

As far binging fluids anything is good except alcohol (obviously) and if you're using water make sure you eat something with it or at least swig a little salt. I finish almost all of my stuffings with water because not only does it stretch your stomach out that last little bit but it also helps your body digest the meal.