SC1 is the one game I never played ~_~1. She was the worst in SC1, and now she's going back to the same style :)
Power wise:
SC2>SC4>SC:BD>SC3>SC1
I think SS is both A and B throw. It's just a normal throw turned into SS using half of the meter. By the way, i think in one video I saw the same thing with Natsu. I think every character can use BE to increase the power of their throws.
As for BE throws - Asta's 2B+G can now do EVEN MORE DAMAGE @_@