A form posting to http:// sends whatever the user typed in cleartext, and browsers now block or warn on it. The padlock on the page says nothing about where the form data goes.
Impact is importance multiplied by the confidence tier’s weight — SPECIFICATION 1.0, RESEARCH 0.7, EMERGING 0.3, EXPERIMENTAL 0.1. Two rules backed by the same class of evidence therefore always carry the same weight, which is what makes the score reproducible rather than hand-tuned.