I believe he meant do anything to get stronger so you can do event. Be it raids or completing main quest line.
It's all about black propaganda for ragnarok difficulty. You don't need to use Mordred, but having black propaganda will help you out, since in rage she will be using burst every second turn.
Weak point is something about 40% extra damage plus you get hit for less(25%?) if you have element advantage.
No. First of all you have 3 different elements there and that's bad.
Well, I am conflicted if I should go with Jean plus black propaganda or Mordred with Ambush/Sniper Shoot. Any advice?