When you say ribbon work and quilting applique, what exactly do you mean? For ribbon work, are you talking about couching (sewing the ribbon or yarn to the quilt top with the longarm as decorative feature)? If so a cup foot is not the proper foot for this work, a couching foot would be a better choice and the shape is similar on some brands. Couching can be done with a cup foot provided the ribbon or yarn is large enough that the needle hole in the foot will guide the yarn or ribbon but if the hole is too large it won't properly guide it through when doing curves so the quilting thread will not catch the ribbon/yarn. Many Innova owners have reported that the trapunto foot is also suitable for couching.
I'm at a loss about your applique comment. The cup foot was originally made for doing pantos from the back of the machine and the cup shape is made to glide smoothly over a quilt top that has uneven surfaces and reduces the chance of getting a pleat on the top when the foot goes over these uneven spots (elements like flanges or piecing like is done in the Mexican Star quilt where curves are achieved by folding over a triangle to form an arc or a quilt with a lot of extra fullness that needs to be quilted down). Personally, I would never do an E2E over applique but I do know some people do and some clients don't have the budget for custom quilting an applique quilt.
Most feet for long arms are proprietary and not interchangable so each brand of longarm have their own special feet specifically for that machine. Not all machines have specialty feet.