This would be one of the two reasons why I generally pre-wash everything. Color bleed tends to be less of an issue with lighter colors and when you wash in cool water. I've done a measured test on the shrink factor of Kona cotton and was surprised at the amount of shrinkage. I love the crinkled look, but that can be achieved just by using cotton batting.
All of my quilts go to individuals who will be machine washing and machine drying. I always warn against hot or overly warm water, but I've seen enough colored water come out of my machine to encourage me to always prewash and except for the Kona cotton, I by all my fabric at the LQS.