Though she moves in the seemingly civilized, congenial world of Baroque music, soprano Julianne Baird has faced vehement booing in Belgium, helped change the history of Bach performance in Boston, and landed behind bars in Maryland. At age 50, this blond, sunny warrior from the front lines of the Handel opera revival discusses these things laughingly. "I love the variety of my life," she says with a certain amount of incredulity. "It's hard to separate what's work and what's play." Variety is a nice word for incongruity. Baird is a genuine star in the world of "historically informed performance" of...