Looks like a good plan. I use water in my pan, but I don't think it will make much, if any, difference. I agree totally with trimming the fat cap to get more smoke to meat contact.
I like apple wood with pork, too. And, no need to foil a butt, IMO.
Starting early is a good idea, and if you are done early, foil it, wrap it in towels, and stuff it in a cooler. It will stay HOT for hours.
Pork butt is very forgiving, so don't stress out. The bone pull test is a good one. It should slide right out. Before pulling on the bone, stick a probe thermometer in it -- not for the temperature, but for the feel. It should go in "like butta."
Don't worry about not pre-heating the cooler, or other minor things. If you have time, do it, if not, don't sweat it.
The stall happens. Don't freak out. It will pass. I think your timeline is reasonable.
Seriously, a pork butt is a good first cook for the in-laws. And, your plan looks pretty solid, to me. So, relax and enjoy the cook.
CD
