I would not wash jelly rolls unless you have an allergy to the chemicals in the fabrics. (I do wash everything else.)
There are lots of patterns to make with jelly rolls, and for some of them the width of the strip really does matter. However, if you're making the 1600 quilt (jelly roll race), then you don't have to worry about the seam being measured from inside or outside of pinked edge, as long as you're consistent. Do cut off the selvages, but don't worry if the strips are not exactly the same length. They probably won't be.