I wash fabrics by machine in cold water and never seem to have much problem other than with the occasional red, and if a red runs it shows on the other fabrics, which I simply re-wash separately. (And that hunk of red is set aside and not used in any quilt -- ever! Reds that run usually wind up in dog bandanas in various sizes that go to the local animal shelter for them to sell along with other dog-related goodies -- my dog already has plenty!)
I'm not sure what I'll do with the fabrics I found today, but they'll wait in the stash with the others. At some point they'll probably wind up in sampler blocks. In recent months I've begun to make random
12" blocks in all sorts of patterns and color combinations, and putting them away. About once every two or three of weeks when I want to take a break from a current project, I get out the fabric stash, set up the sewing machine, and spend an evening making blocks all in different patterns, so the pile of blocks is building up nicely. Most of the blocks will eventually be part of sampler quilts, while others may wind up in throw pillows or tote bags.