The English singer is invigorated by the creative challenge of his first Broadway musical, 'The Last Ship.' He's got an album of some of the songs, and a tour with Paul Simon is planned. On a recent weekday afternoon, Sting was sitting in a Burbank dressing room, quietly reading on a tablet computer as he waited to make an appearance on "The Tonight Show With Jay Leno." A chat with Leno wasn't the English singer's only reason for being in L.A.; two nights earlier, he'd entertained a crowd of celebrities and show-biz executives at the Los Angeles County Museum of Art's annual Art + Film Gala. Asked how the gig went, Sting put down the tablet, took off his glasses and reported that no one had asked for his or her money back...