Anyone knows how the cheats work? I've used ctrl+gabbi and a message appears, but I can't use any cheat before that. I usually don't use cheats, but these SAM bases are f**** difficult and I can't take the mother***** snipers down without losing half of my men.

Does the message say "cheat mode level2 active"? If so then you just need to press and hold ALT and the letter of whichever cheat you want from the same screen you just entered Ctrl gabbi from. If this is what you have already done then I'm not sure.

Taking SAM sites is all about the point of entry to the location.
Choose it wisely, position your people and advance slowly, 1 merc at a time.
You should be able to take all of them with 1 team.
My points of entry:
SAM sector south of Chitzena:
I enter the sector from the south and cut a hole in the fence below the corner of the building.
After going through it I have to people climb the roof of the building.
By now you might have been noticed by the enemy.
I move 2 peope the north west of the building, 1 along the east side till halfway that side and position 1 at the corner of the building to target both sides of the building.
Than I have the 2 on the roof slowly advancing and let them take out the enemies.
The ones along side the building will take out everyone who gets in their line of sight.
SAM sector east of Drassen:
I enter from the south or west and slowly move towards the gate.
I position my people carefully behind trees and such and have them lay down.
They're all camouflaged.
Than I fire 1 shot so they come running out.
From there on it's mostly a game of target practice.
SAM sector south of Cambria:
This is the toughest 1, but that might be due to the fact it's always the 3rd SAM site I take.
I enter it from the north and advance to the fence.
I cut a hole in the fence and go through it.
Shortly after you'll get noticed.
Taking cover is key here and keep the west, east and south sides covered by 2 mercs each.
Preferably in such a way you cover more than 1 side per merc.
Advance slowly towards the buildings and gate.
The only tough nut to crack from there is entering the building in the south.

That's what I've done, but it doesn't work for me. =(
How do you detect all mines? Trevor usually detects every trap he encounters, but he is blind when it comes to mines.

I'm not sure if I ever encountered mines in the SAM sites near Drassen and Chitzena.
As far as I can remember the 1 south of Cambria has them.
By the time I take that one, my mercs have leveled up enough to spot them.
I also have 1 who's carrying a metal detector.
Fidel spots mines straight on and Steroid can spot them too.
My custom merc and Burns sometimes spot them, but not always.
So I send Fidel and Steroid in front when I clear the mines.
Due the the fact I enter from the north and cut a hole in the fence, I don't encounter much mines there.
I think the west and east sides have more mines and there are also mines near the buildings and gate.
Most mines near the buldings are between the buildings and the fence.
As for Trevor, I used him only once.
I prefer Fidel as he was also 1 of mercs in JA1.