In advance: Make caroling book and snowman arms. For book, cut graham cracker into two 1 1/4 x 1 in. high pieces. Ice one side smooth; let dry, then ice the other side and let dry. Pipe in top and bottom edges of each piece with tip 5; let dry. For arms, cut licorice into six 2 1/2 in. lengths; for fingers, cut twelve 1/2 in. lengths. Cut one end of each finger diagonally; attach 2 fingers on diagonal end to each arm with a tip 2 dot. Let dry.
Bake and cool 1-layer half round (2 in. high) and 3 snowman cakes. Ice half round smooth. Spatula ice fluffy snow at bottom of cake. Pipe tip 3 message.
For snowman with earmuffs, trim off hat and top of head. Spatula ice snowmen and position on cake. Pipe tip 2 eyes and outline mouths. Add tip 3 pull-out noses, dot cheeks and buttons. For earmuffs, cut a 3 in. piece of licorice. Pipe a small tip 8 dot on each side of head; insert licorice and overpipe ends with a tip 8 ball. For top hat, pipe tip 12 band hat and tip 8 outline brim. Add tip 5 string hat band. Pipe tip 12 pull-out stocking cap with tip 3 zigzag trim. Add tip 3 dot pompom. On earmuff and stocking cap snowmen, pipe tip 8 outline scarves with tip 2 outline fringe. On top hat snowman, pipe tip 47 band scarf. Insert book pieces, raised so that edges meet in a V-shape; pipe tip 5 outline binding.
Insert arms in earmuff and stocking cap snowmen, trimming as needed. For top hat snowman, cut two 1 in. long licorice shoulder pieces; insert on each side. Trim arms to 1 3/4 in. long; attach hand portion to book and arm to shoulder with tip 2 dots. Pipe tip 2 and 3 dot snowflakes; add tip 10 ball bottom border.