I am also brand new to LAing and have not done anything for anyone else, YET. I plan to quilt for others. If I had someone who was not happy with my work I would want to know as well so I would not repeat the same mistake.
Regarding the fold in the batting, My rack has the batting hanging loose, it is not on it's own rail. I "float" it on the quilt backing then the top. However with each advancement of the quilt I check it. My rack has a wonderful feature in that I can lift the rail that the quilt top is on to actually inspect the batting to ensure it advanced smoothly with no wrinkles. It can happen depending on the rack set up. Not all LA racks are the same, similar yes but some have very different features.