If it is for the design aspect and not the operation of the LA, some questions would be: (and most of these may be discussed anyway.)
1) How to know what design to use on what pattern ?
2) What color thread to use on what color fabrics should it blend in or stand out?
3) How to determine how tight to make the stitching (some batting fabrics call for closer quilting
4) What's the cheapest way to practice on quilts. i.e. even practicing on solid fabrics require backing fabrics and batting to be used.
Have fun and let us know what you learned.
I'm a Longarmer working on customer quilts but always learning.