Preheat oven to 375°. In a small bowl, mix wafer crumbs and sugar; stir in butter. Press onto bottom and 3/4 in. up sides of a greased 10-in. springform pan., In a large bowl, beat cream cheese and sugar until smooth. Beat in flour and vanilla. Add eggs; beat on low speed just until blended. Pour into prepared crust. Place pan on a baking sheet., Bake 30-35 minutes or until center is almost set. Cool on a wire rack 10 minutes. Loosen sides from pan with a knife. Cool 1 hour longer. Refrigerate overnight, covering when completely cooled., In a large heavy saucepan, melt caramels with milk over low heat; stir until smooth. Stir in walnuts. Cool to room temperature. Remove rim from springform pan. Serve cheesecake with caramel sauce.