1. Disrupt all surveillance equipment: medium, hard 
2. Copy Goldeneye key and leave original: easy, medium, hard
3. Photograph main video screen: easy, medium, hard 
4. Get personnel to activate computer: hard 
5. Download data from computer: hard 

Open the door in front of you and quickly kill both guards. If you're slow, they'll hit sound the alarm. Pick up their stuff, KF7 Soviets, and use the PP7 again to knock out the red alarm on the wall. 

Turn around and head to the room from where you started. There's another door there, and behind it is a generator and a surveillance camera, quickly open the door and blast it to pieces (you can nail it with one shot if you're good). No alarm means you've succeeded. 

Go back to the second room you were in. You'll see a guard passing. Reload the PP7 and take him out with one shot to the head. He's got a security keycard. If he doesn't, another guard in the near vicinity will. Knock out the camera outside and to the right. 

With the room you just departed behind you, turn right. You'll reach a room that's also part cave. Three men will guard it. Kill them and eliminate up the camera. Use your PP7 for quite death and few enemies, or your KF7 for more enemies, plus better enemies as well, like the Klobb and DD44s. 

your left is a hallway that leads to a staircase. That staircase leads to the main room with Boris, the key you need to copy, and a map of the world, of which you'll need to take a photograph. But you can't go in yet, there are simply too many armed men in it. 

Leave that cave when the coast is clear. You'll find very close to you a gray door that leads to another gray door inside it. Go inside the first door, but not the second. Look through the window. There are three men, and a mainframe. Don't use any grenades, and make sure not to blow up the mainframe. In the difficult level you'll have to bring Boris up here and turn on the computer. Two men are to your right and one to your left. Open the door and spray them with bullets. Collect their weapons and head to the main room. At this point, you should have eliminated everyone in the hallways and other rooms, except for the main one. 

Round the corner to your left and slowly use your silenced PP7. A few guards should be in various places around the room. One's directly to your left, another straight across from you -- now's a good time to switch to the Phantom. To your right is a staircase, so run up it and kill off the three enemies in it. The room you're in is a split floor and across from it is a similar one across the large main floor. Two men are in it. Run over there and blow out the camera. That should complete objective A. This should all be done quickly, so that Boris doesn't run away. Initiate conversation with him for the hard level of difficulty. He'll lead you to the mainframe room. Now, while you're in the main room, you'll see a giant world map. While you're following the ever-so-slow Boris, switch to your camera and take a shot of the map, completing objective C. Let him type in "knockers," and then switch to your data thief. Press Z to enact it, and wait until it's completed. Boris will have turned on the alarm, so prepare to face dudes with DD44s. 

Now run back to the computer in the main room where you found Boris. Pick up the key and switch to your key analyzer. Copy the key by pressing the Z button and your primary objectives are now complete. There is one door to the right of the world map. Enter this door which leads to a staircase where at least two guards are standing at the top. Use your C button to aim high. That's it, spy guy.