Kacey Musgraves.In addition to serving as the musical guest on the March 2 episode of NBC’s “Saturday Night Live,” the 35-year-old country-pop star just announced her global ‘Deeper Well Tour’ in support of her upcoming album with the same name.Midway through the 35-concert North American leg of the tour, she’s slated to headline at Newark’s Prudential Center on Monday, Sept. 9 and Brooklyn’s Barclays Center on Friday, Nov.