As far as your thread choices... keep it white. That pattern expresses itself via the points and the play among the color subtleties of your background and focus fabrics. To quilt in any other color but white, it will ruin that effect. I would finish the top, put it away for awhile, bring it out and decide then a plan for quilting it. Lay it on a bed for awhile un-quilted and you will get your answer as the best way to finish it. Or make lap quilts out of it.
tim in san jose