Will Just Cause 2 have cheats for ps3 and multiplayer?

i was playing the demo of this game on my ps3 and i just love sand-box games like Mercenaries 1 %26amp; 2 and i was wondering if they are coming out with cheats or DLC for this game and is this game going to have multiplayer and also if you didnt pre-order the game can u still get the gun and monster truck.|||No multiplayer which is a bit of a turn off for me.