Posted this once before, but here goes again:)
At each map reset, only those enemy installations at the front lines are known (visible on clipboard map. Vehicle spawn points are there, but unless you can see the field from the remote spawn point, you won't know in which direction to travel.)
Enemy installations become visable on clipboard map once someone has selected a photo recon plane, overflown the area, and successfully returned to base (to develop the film

)
Of course perk points would be awarded upon completion of the mission.