Get your air guitar ready.It promises to be a music-filled weekend at Cumberland Caverns and in downtown McMinnville.To coincide with the annual three-day taping of Bluegrass Underground at Cumberland Caverns, a number of activities are scheduled around the downtown area this weekend. Those include live music at Collins River BBQ and Smooth Rapids Campground, a whole hog smoking, and Calfkiller beer tasting.“We want to welcome all the people who are here to see Bluegrass Underground and give them something to do before and after those shows,” said Christy Ross, president of the Downtown Business Association. “Downtown stores are going to be staying open extended hours and we’re going to be running a number of specials.