How does the mission's documents/intelligence work?

Question

At the beginning of each mission, you can buy some information or strategic assets (photos, maps, access to cameras, ...)

1. In what way can it help you ? For instance, if you buy a map, will you be able to see it during the game, through the HUD ?
2. Do you have to buy it multiple times ? Since the missions are all supposed to be "unique", does it mean that you have to buy the document again each time you play it ?

Answer 1

No you cannot see the map during the game. It gives you information about the mission before starting the game. The information is quite useful, for example, people carrying keys you can take and alternate paths.

You need to buy the assets you want each time you enter the mission lobby. They will only last for one attempt and are lost when you start the mission.