Concerning the folding of quilts, one of my old QNM magazines had a one-page article on a method that is highly recommended. I'm probably not remembering the entire method correctly, but it involved making the folds on the bias rather than the usual length and width. I know you had to fold in corners to do this. Basically all of the folds end up on the bias grain, which is stronger, so you don't get the indelible imprints so common if you fold on the straight-of-grain. With the bias, many different threads are taking the stress of the fold rather than just a few. You would still need to take out and re-fold periodically.
You absolutely do not want to store quilts next to wood, cardboard or paper (unless the cardboard or paper is archival quality or acid-free). I like the idea of storing them in cloth pillowcases.
An alternative to folding is to take a length of PVC, wrap it with batting, and roll your quilt instead of folding it. There will still be uneven stress on the quilt, with the inner layer getting more wrinkles than the outer layer, but you probably wouldn't need to re-roll as frequently (I would switch rolled-in sides) as you would want to re-fold. You would still want to cover the roll with sheeting, and it would need to be stored propped up.
Some people store quilts on a bed in a spare room. You can store lots of quilts this way, and (with the exception of the sides hanging down) lying flat is the least stressful on the fibers. A sheet on top keeps them clean too.
Mary