Apple, cherry, peach, alder are all good choices for pork.
Loins cook quick some prefer a lower temp in the pit to maximize time in the smoke. 200-225.
Do not over cook the loin. You will want to pull the loin when the IT hits 140-145. Foil and let it rest a good 30-45 minutes before slicing. This will insure that you have a nice moist cut. Yes the meat will have a slight pinkness to it. This is due to the smoke and the fact that people have over cooked pork for years. 145 is the safe temp for pork as recommended by the USDA.