Sorry, I can't help you with the corduroy question, I have never used corduroy in any of my quilts. Maybe you could make a sample block and wash it a couple of times and see what happens. I do that when I am not sure how a fabric will work out in my quilts.
I love your denim quilt, it really turned out nice.
I made a denim quilt for my grandson when he was born, but I never thought of making it into a rag quilt. I used my serger to do the seams and I added a flannel backing. I unstitched the pockets from the jeans and then stitched them on coordinating blocks so they could be used to hide toys. It was so heavy that I just tied it instead of quilting it.