Vortex of Return, Ritual of Rebirth & Afflictions
 

1>Does Vortex of Return work on all units on the battlefield or only those under the command of the caster?

2>Ritual of Rebirth says it doesn't work on undead or lifeless units and makes a dead hero into a lifeless undead mummy, but Ritual of Death also says it can be used on the same unit multiple times. So it won't work on undead/lifeless heroes, except mummies?

3>How are new afflictions determined if a unit already has an affliction so for example, unit already has chest wound & gains a new affliction...
a>roll for new affliction determined to be chest wound so no new additional affliction since you cannot have 2 chest wounds.
or
b>new affliction determined to be chest wound and since you cannot have 2 chest wounds reroll for a different new affliction.

4>Does "Heal Units" and "Requires Lab to Heal" work for all units in the province including those patrolling outside a castle or only those inside the castle?

Re: Vortex of Return, Ritual of Rebirth & Afflicti
 

1) All friendly units including commanders. As far as I know nothing "in battle" is contingent on which commander troops are assigned to (other than "guard commander" I suppose)

2) Correct, I think the game probably counts them as their original type rather than an undead mummy.

3) No idea, impossible to test but units with a lot of afflictions don't seem to stop getting new ones so I'd guess b.

4) Yes, all units. If your armor is destroyed by ie. "Destruction" however it will be repaired at a rate determined by the unused resources in the province you're in.