Prisoner Exchange in Halacha | Hear from a brother of one of the hostages

Are you permitted to pay for captives more than their worth?
Are you allowed to release terrorists in exchange for prisoners?
Can you put other people’s lives in Sakanah to save a life?
How many more deaths were caused historically by terrorosts released by prisoners swaps?
Can you wage war to save hostages at the expense of more lives than the ostages themselves?