To use Press'n seal you trace your stencil onto it and then place on your quilt, sew through and pull it off. It could be a pain picking bits out of the stitches, so try first. You could use tracing paper/baking parchment and secure it to the quilt with masking tape which would tear off easily.
You use a Hera marker before sandwiching the quilt, I just tried it on dark flowery fabric and it's really hard to see so forget that
Another thought is Crayola washable fine line markers but again test first one of the colours is hard to remove but I can't remember which