I agree. And it's more successful with long-time businesses that have built a reputation for excellence. New businesses without a track record may have to entice participation with low prices or extras.
I don't use a recipe, but just substitute Kahlua for some of the liquid in my basic buttercream. I also add powdered instant coffee and cocoa, then sample and add more if needed. Then sample more. I can only suggest you start with your favorite buttercream recipe and keep a spoon handy.
Time management? You're a mom and a full-time student with a part-time job. I assume you also have household responsibilities and a personal life. If you enjoy cake decorating, my only suggestion is to give yourself a break. Keep cake decorating as a fun distraction and not as a business.
If you're not happy with the recipe, try another. Kahlua cake has no standard of identity, other than it should include Kahlua (even if it's just a teaspoon). My bakery made a Kahlua cake - it was a chocolate cake I'd adapted from a Hershey recipe. And it was one of our top-selling wedding cakes.