Frozen or on the rocks is for amateurs, now that W. Park Kerr is on the scene. Kerr, a ninth-generation Texan with agave in his blood, really knows his way around a margarita -- as he reveals here with more than 60 recipes for his favorite tequila-kissed concoctions. Patio party or swanky soiree, the opportunities to cha-cha with Senorita Margarita are many. There is, of course, the classic, the timeless, Ultimate Margarita. Witness also the tropical...