Quivering Palm

The new QP has me confused, because of the word "alternatively". 

Is it saying that after spending 4 FP's and I hit, I can walk away and decide later to end them by my force of will. No other attacks required?

The alternatively part says I can end it by simply forgoing one of my multiple attacks. What's the point of that, if I can will it to end in the above question?

Also, can you also spend additional FP for FoB's in this combat, thus 5 FP's? 

Great answer Wag