Make the pork: Mix the brown sugar, salt, pepper, coriander, allspice, paprika, garlic powder, onion powder, mustard powder, dill, celery seeds and red pepper flakes. Rub the pork all over with the mustard, then the spice rub. (You may not need all of the rub.)
Soak the wood chips in water at least 30 minutes; drain. Heat a charcoal grill and prepare for indirect grilling: Bank the coals to one side, leaving the other side empty. Set up a drip pan on the empty side. Let the fire burn down to a low heat (225 degrees F to 250 degrees F).
Scatter some of the wood chips over the hot coals. Put the pork on the cooler side of the grill, over the drip pan, fat side facing the heat. Cover and cook until a thermometer inserted into the center of the pork registers 160 degrees F, 5 to 6 hours, adding a handful of wood chips every 1 to 1 1/2 hours and more charcoal as needed.
Meanwhile, make the barbecue sauce: Combine the vinegar, brown sugar, ketchup, hot sauce, red pepper flakes and 2 teaspoons each salt and pepper in a nonreactive pot. Cook over medium-high heat until the sugar is dissolved, about 5 minutes. Refrigerate until ready to use.
Remove the pork from the grill, wrap in foil and return to the cooler side of the grill. Cover the grill and cook until a thermometer inserted into the center of the pork registers 195 degrees F to 200 degrees F, 3 to 5 more hours, adding more charcoal as needed.
Remove the pork from the grill and let rest 30 minutes. Carefully unwrap and pour off any juices. Pull the meat into chunks, discarding the excess fat and bone. Toss with half of the barbecue sauce; season with salt and pepper. Serve with curry pickles, bread and the remaining barbecue sauce.
Toss 3 thinly sliced English cucumbers with 2 tablespoons kosher salt in a large bowl. Refrigerate 1 to 2 hours, then rinse and transfer to a large glass bowl or jars; add 1 thinly sliced large onion. Combine 1 1/2 cups each granulated sugar and white vinegar, 3/4 cup apple cider vinegar, 1/4 cup light brown sugar, 2 1/4 teaspoons mustard seeds and 3/4 teaspoon each celery seeds, curry powder and red pepper flakes in a nonreactive pot. Cook over medium-high heat until the sugar is dissolved. Pour over the cucumbers and onions. Refrigerate at least 1 day and up to 2 weeks.