Hello, to awnser you about the red bar, yeah, it’s limit break. When you take damage, the limit break is going up. And when it’s full, you can do ONE very powerfull attack or UBER support. ( revive everyone, +60% to every stats / -60% to every enemy stats.. )
But you will have to learn these first in the skill section.
 "Sephiroth701"){kind=small}