The defense subtraction works with her range, yes. A crossbow bolt is as a good as stake to a vampire.
Moving it to the top of the power is a good idea, though.
On SuperStrength, her strength level is well above that of a human, even topping most vampires. When sparring with a trained soldier in good condition, she has to hold back most of her strength just to keep from seriously hurting him.
With the Big Bad power, the blanks are only adding, on average, a half-a-skull an attack. I'm just worried that the power, as is, is not very exciting. I don't want her to be too powerful (low-to-mid 200s would sound about right), but I don't want to end up with a power that's boring or has too little an effect on the game.