Can't offer an opinion on muslin for you as I've never used it for a quilt backing - only other odd projects. I usually use typical quilting cottons to coordinate with the front of my quilts. As to batting I almost exclusively use Warm & Natural. Purchased a bolt at Joann's last year with a 50% off coupon and it's keeping me going nicely. I hand quilt. I find the drape initially to be a little stiff but it does soften with use/washings. It can be a little more difficult to hand quilt but no more so IMO than the 100% cotton Quilters Dream that I'm working with currently. I like 100% cotton batts as I like the crinkley look as well. Can't tell you shrinkage rate with the W&N - hasn't been a consideration for me. If I was looking for a very drapey batt and $$ were not a consideration I'd probably try silk. Might still one of these days on a small project. When handling silk batt on it's own it's incredibly soft/drapey but also very pricey. Again, no idea of shrink rates with that.