Imo pulling the meat @195 gives you inconsistent tenderness. There are a lot of muscles in a pork butt and they won't all be soft at that temp- especially if it just hit that temp and hasn't rested. Take your butt off the shoulder at 205, foil it, and hold it in an insulated container until you're ready to pull it and serve. Oh and +1 for going by feel or buy when the bone pops out. You can use a skewer or thermapen to check for tenderness. Note that will take a lot of practice.
Right on. It isn't a temp, it is about tenderness. You can foil at the stall (probably about 170) to speed things up, but you need to cook the pork until the bone twists easily, and a fork put into the meat twists and pulls the meat with little effort.
That's if you are cooking and serving. If you have to hold the meat, yeah, put it a cooler - but it will keep cooking unless you let it cool down on the counter below 150. (but not below 140 for more than a couple hours.)
Crap. I didn't address your original question. It's not the vinegar, or the outer fat - just cook it up until the meat is loose on the bone and let it cool enough where you can stand to pull it without burning your fingers and pull it. It will be good.