Schumann's Symphonic Etudes is a monumental romantic work, which I love very much and have played it quite often. I certainly believe it's a good idea to learn the posth. variations as well. You can play them inbetween the Etudes and I strongly suggest to you to follow the order of Alferd Cortot, that seems to work perfectly from my experience with the audience AND the performer. Very important is to decide how long the pauses between the Etudes will be. Sometimes it is effective to make just a short pause, but in other cases you need to make longer ones, in order to allow the listeners to understand the music better. Also, use the repeats as a "test" for your fantasy to do different things in dynamics, phrasing, pedalling etc
Good luck!