does vader crew card by pass shields or would it just take one shield away?

Vader inflicts damage; the process for suffering damage is on Page 16 - take a shield if it has one, deal a damage card otherwise.

So Vader's damage - both to the target and his own ship - will hit shields first.

The only effect in game, off the top of my head, that bypasses shields is the Proton Bomb because it explicitly says to deal a damage card as opposed to suffering damage (be it hit(s) and/or crit(s)). Everything else follows the normal damage rules as posted above by Buhallin.