If you empty your clip, can't you be accused of excessive force?
In the civil trial, using harsh language against the Bad Guys will be treated as execssive force... The Bad Guy's attorney will argue against everything one does in a self-defense situation; this is why it's not a good idea to have, for example, door signs like "I don't dial 911, I dial .357" or "Protected By Smith & Wesson".
Not if that's what it took to stop the threat.
Not advisable though because a: You ought to pack a powerful enough piece and be a good enough marksman that multiple shots aren't needed and b: "Spraying and Praying" can put bystanders at risk. No one is going to call you a hero if you kill innocent people trying to protect yourself.