Making a cake for a friend surrounded by matching cupcakes. I baked them in the foil lined cupcake liners (red velvet is oily). She taking the cake to a restaurant after I drop it off, so I'd like to feel ok that she can travel with it all setup. Can I attach the cupcakes with royal or chocolate? The cake board will becovered with MMF.

Also - I've made approx. 4" flat gumpaste guitars that I thought I would attach toothpicks to with chocolate. Anyone done this? Think it will work?

I don't see why you couldn't attach them with either one.