[K]

1. Yes.

2. SCs are best dealt with by using spells, or a combo of spells and high attack units with armor negating or armor piercing damage. A few suggestions are Soul Slay + Penetration items, Petrify, Incinerate....the list goes on. Spells with MR checks need penetration items, but there are plenty of killer spells that don't check MR or have their own weird checks (Magic Duel compares base Astral v. base Astral, so if you are an Astral nation you can kill Golem SCs pretty well.)

In general, fighting SC with SCs is wasteful. SCs are for cleaning up piles of regular units and occasionally taking provinces alone.

3. Maybe. Undead with the Lifeless tag do not regenerate. Undead without the Lifeless tag include banes, vampires, and a few others. I believe that MA Ermor has some ethereal undead sacred that are not Lifeless.

4. No.