Q. Does Hard to Kill reduce the damage taken for the purposes of irreducible damage?
A. No. Hard to Kill prevents a model’s Health from being reduced and does not reduce damage.
Q. If a model’s Slow or Stunned Condition are ended during its Activation, by an effect such as Shrug Off, do the effects last for the rest of the Activation?
A. No. If Slow is removed, the model’s Action limit is immediately increased back to its normal value and the model may continue its Activation as normal. If Stunned is removed the Bonus Actions it has already taken that Activation no longer count towards its Action limit.