http://www.gamefaqs.com/console/ps3/code/944401.html

Can someone explain what these codes do.
1. I am guessing that the codes below are for different missions and the top one releases them all?

2. Is there a certain way to activate them in game after using code?

3. Can I use the codes right before the area of darkness?

Thanks for the help everyone!

Not sure about the top one, but the Bonus Missions require that you be in Pala for the North, and the South's main city if you're there. You get a cell phone call in the cities and the objective shows up on your map. I don't think you can use them before the Heart of Darkness, since you would've missed the North phone calls.

I can't just go back to the north and activate it?

Once you go to the South, you can't go back to the north. You may be able to go to the South's main city and do the last three, but I'm not sure.

Wrong. you can drive back at any time, no problem...