Thanks for playing!
By "stilted to start", are you referring to the time it takes to get up to full speed from standing still?
For the hitboxes, most attacks generally use the weapon colliders, which are set to follow the bounds of the weapon quite closely. This is meant to allow for some attacks to be avoided by spacing or using other moves to move your body hitboxes, but in practice it's possibly too tight that a lot of attacks tend to miss.
For the double swings, are you talking about the repeated ones where she spins, or the teleport attack?