I would not pre-wash. You don't need to purchase starch in a quilt shop; your local grocery store or Walmart will carry it. Should be in the area of laundry detergents. I would get a heavy spray starch. Best Press does not stabilize the fabric as much as spray starch. However, if you don't pre-wash, there may be enough stabilizers in the fabric so that Best Press is enough.
Even with starch, pay attention to how you handle the pieces while you sew. You don't want to be rough with those edges. Some machines are better than others at feeding fabric without stretching it.
I do not worry about fabric shrinkage with fabric that is not pre-washed. This is because quilting binds the 3 layers of the quilt together which means that the batting will not allow the fabric to shrink more than the batting shrinks. The quilting does need to be moderate -- every 4" or so. If your quilting lines are 12" apart, then the fabric has enough space to shrink more than the batting and cause distortion.
I do the first wash of the quilt in Synthrapol so that any dye bleeds do not stain the other fabrics.