FOR TEN YEARS, they exchanged notes, letters, faxes, and phone calls. Stephen Sondheim would contact him, and Paul Salsini, the founder and editor of The Sondheim Review, would respond. And vice versa. Now, Salsini, a Milwaukee journalist, has described his unlikely long-distance relationship with the fabled composer/lyricist in Sondheim & Me: Revealing a Musical Genius. The memoir includes the dozens of notes that Sondheim sent Salsini...