#1-2. As soon as the mission starts, open your nanovisor to tag the collectibles along the way. Right in front of you is the first blackbox of the mission, and a few steps away from it is a propaganda poster. Above the poster is a wreckage where a datapad and ammo crate is found. Continue forth and you'll find another blackbox beside the corpse in the bus wreck.
First few collectibles of the last mission
#3. While still inside the cavern, continue along the path and you'll find another blackbox, past the ledge where you need to climb up.
#4. After connecting to the first mind carrier and on your way to the next objective, you'll come across another CELL weapon cache and more supplies. You'll find a blackbox in an open empty case.