What? This has nothing to do with SVism.
Second proposition is only morally certain, not dogmatically. Could be that your priest isn't valid for one reason or another.
Yes, but absolute moral certitude. For
practical purposes of faith, because we offer adoration to what looks like bread but we know is not (hypothetical notwithstanding).
We also know that the men commonly claiming to be true popes cannot be so, because the Church could not violate Mortalium Animos to the universal Church in all Her organs of the magisterium.