I wash everything before taking it into my sewing room. If I think there's a chance colors will run, I dump a bunch of distilled vinegar into the load. Since you're supposed to wash quilts in cold water, you may want to pre-wash the fabrics in cold as well. No fabric softeners. If I'm pretty sure colors will run, e.g., batiks, I dump in a BUNCH of vinegar AND a couple of dye-catcher sheets. I pre-wash for a number of reasons, primarily to pre-shrink and set the colors, but also to make sure the fabric will hold up to washing in the first place. Other people will have as many reasons to not pre-wash, and you'll gradually figure out what you're happiest doing.
With red, white, and blue, you probably would want to wash them separately.