Respawn a locked Royal Sorcerer Navlaan

After a little time has passed, a tombstone will appear where you killed Cale. If you interact with the tombstone, you can pay souls to speak with Cale's spirit, which will allow you to obtain the key.

This same technique works for all (or almost all?) NPCs in the game. If the NPC in question had items for sale, you're also able to browse their wares this way.

Absolutely.

I have been both parried and crit shield bashed by the skeletons in Hunters Copse. I am unsure if these are the only enemies that will do this, but it is definitely possible.

It is to note that there is still the destinctive crit sound that plays every time this happens to me.

Also, there is a recovery period of every attack in which you will take increased damage. If you are mid swing when you are hit, this will add to the overall damage output of the enemies attack (regardless of weapon).