That's 3 questions Turtlemom
As for sage, I just use my Wilton Juniper icing color. It doesn't show up as dark as what the label says. I used it for my brother's wedding, which sage was one of the colors, and it worked perfectly. Just remember to start out with a little color at a time until you get the desired color.
As for cupcake cakes, you can do it two ways: 1) Bake individual cupcakes then place in a design of your choosing. Ice the top of all and fill in the cracks with icing so the top is uniform-design as desired. OR 2) Place cupcake liners in desired shaped pan (square, oval, round, etc) then fill liners with batter and bake. When the cupcakes bake up they will all be connected so it makes it easier to ice the top (no filling in the cracks). Design as desired.
Have fun and happy baking!