Not necessarily, they might not own the tool, just paid for someone to use it on the phone.

AFAIK, the exploit only works on older iphones. It'll quickly lose value going forward.

You can't put a price on national security. Never mind, they just did and they got to define national security as well.

There is no indication that it wasn't what had been claimed they could always do, and that's physically clone NAND gates. Remember, the FBI wasn't after data in the first place, they were after a legal precedent.