Perfect Dark Zero cheats and cheat codes for Xbox 360

Getting unlimited ammunition for plasma gun and rocket launcher
Get a rocket launcher or a plasma gun.
Get on the gunner position on a hovercraft.
Press Y, this will swap it with the M60.
You should now have infinite ammo.
You choose to put on the hovercraft. 
You can use this trick to get a free M60 on any level.

Unlock Dark Agent
Finish the game on Perfect Agent mode.

Unlock Xbox Live gamer points:
You can get achievements for doing certain tasks in single and multiplay modes. 
These achievements count to your gamerscore for your gamercard.
Complete the next tasks to unlock 20 points (max. 1000 points). 

Finish 1 Co-op misson on Dark Agent Difficulty
Finish 1 Solo misson on Dark Agent Difficulty
Get 10 kills using explosive in any Multiplayer modes
Capture 10 Flags in Capture The Flag mode
Get 10 Headshots kills in any Multiplayer mode
Get 10 kills in Killcount mode
Get 10 kills in Team Killcount mode
Get 10 Melee kills in an Multiplayer mode
Survive 10 minutes in Onlsaught mode
Infect 10 Players in Infection mode
Survive 10 Rounds of Eradication mode
Get 10 Sniper kills in any Multiplayer modes
Score 10 points in Territory Gain mode
Destroye 10K CR of property in Sabotage
Get 100 kills using explosive in any Multiplayer modes
Capture 100 Flags in Capture The Flag mode
Get 100 Headshots kills in any Multiplayer mode
Get 100 kills in Killcount mode
Get 100 kills in Team Killcount mode
Get 100 Melee kills in an Multiplayer mode
Survive for 100 minutes Onslaught.
Infect 100 Players in Infection mode
Survive 100 Rounds of Eradication mode
Get 100 Sniper kills in any Multiplayer modes
Score 100 Points in Territorial Gains mode
Destroye 100K CR of property in Sabotage
Get 1000 Explosive kills in any Multiplayer Mode
Get 1000 Headshot kills in any Multiplayer Mode
Get 1000 Kills in Killcount Mode
Get 1000 Kills in Team Killcount Mode
Get 1000 Melee kills in any Multiplayer Mode
Infect 1000 Players in Infection mode
Survive 1000 Rounds of Eradication mode
Get 1000 Sniper kills in any Multiplayer Mode
5 Co-Op missons on Dark Agent Difficulty
Finish 5 Solo missons on Dark Agent Difficulty
Finish Co-Op on Agent Difficulty
Finish Co-Op on Secret Agent Difficulty
Finish Single Player on Agent Difficulty
Finish Single Player on Dark Agent Difficulty
Finish Single Player on Perfect Agent Difficulty
Finish Single Player on Secret Agent Difficulty
Finish Co-Op on Dark Agent Difficulty
Finish Co-Op on Perfect Agent Difficulty
Play 10 Dark-Ops games
Play 10 Deathmatch games
Play 100 Dark-Ops games
Play 100 Deathmatch games
Play 1000 Dark-Ops games
Play 1000 Deathmatch games

Location - weapon:
The next list contain the levels for all the weapons.
Sewer Retrieval - CMP-150 (SMG 2)
Trinity Infiltraiton - Combat Sheild (Sheild 1)
Nightclub Stakeout - DEF-12 Shotgun (Close Combat 2)
Nightclub Stakeout - DW-P5 (SMG 2)
Trinity Escape (off dead ally) - FAC-16 (Assault 2)
Nightclub Stakeout - Falcon (Pistol 1)
Nightclub Stakeout - Frag Grenade (Thrown 1*5)
Lab Rescue - KSI-74 (Assault 2)
Trinity Infiltration - Laptop (Assault 2)
Mansion Infiltration - M60 (Heavy 3)
Rooftops Escape - Magnum (Pistol 1)
Mansion Infiltration - Magsec 4 (Pistol 1)
Temple Surveillance - Multi Mine (Thrown 1*5)
Trinity Infiltration - Phychosis Gun (Pistol 1)
Temple Surveillance - Plasma Rifle (Heavy 3)
Jungle Storm - RCP-90 (SMG 2)
Bridge Assult - Rocket Launcher (Heavy 3)
Outpost Rescue - SuperDragon (Assault 2)
Nightclub Stakeout - UGL Liberator (SMG 2)
Mansion Infiltration (red triplaser room) - Viblade (Close Combat 1)