It is a bit like the wierdstone in that it can maintain spells/boons.
As you note it can also summon reborn warriors, unless the scenario states otherwise I don’t think you can start with any in play.
Regards having more models without buying the cauldron again, maybe use Drune half dead, or regular warriors, or models of undead from another company?
For an official answer?
I have come to the conclusion that there is little support if any.
In fact I made a FB group for Slaine a few days ago because of the lack of content here, it is a new group and still small, but you are welcome to join:
https://www.facebook.com/groups/slainethegame
