Julia launches her new NET series with simultaneous publication of the recipes-a real treat for hapless scribblers. Like her last book, From Julia Child's Kitchen, this drifts away from traditional French cuisine and concentrates on American occasions and availabilities--cocktail party items, roast beef dinner for the boss, an outdoor barbecue of butterfield leg of lamb. In the past, the program's recipes were geared to half-hour velocities and for this year's shows they still are; but here complete recipes for whole menus are included because off-camera cooks can manage them. Anyone can tackle the potato salad or one-dish meal of New England fish chowder; most recipes, however, are more demanding, although they won't tax her votaries. And the color photos (on 8"" x 11"" pages) are a significant bonus, showing the inexperienced how to pull stems off spinach leaves or bone a chicken, and more ambitious souls how to prepare Choulibiac or Chicken Melon Expect lots of company.