“Deploy to a region you occupy. Cannot move or be moved. If attacked, Cauldrons take damage last. At the start of each round, add 1 Tyro from the discard to regions with a Cauldron.”
Can you deploy a Cauldron to a deployment zone? (yes)
Yes, but it wouldn’t be as useful there as in other regions, since deployment zones aren’t counted for control and cannot be attacked so many of the benefits of the Cauldron would go to waste.
If a region has multiple Cauldrons, does it get multiple Tyros at the start of the round? (no)
Each region with at least one Cauldron in it gets one Tyro at the start of the round (if there is a Tyro in the discard to deploy). A region with multiple Cauldrons still only gets one Tyro each round.