You have to complet the game on legendary
beat campaign on legendary
this you can unlock by playing on HARD diffuculty on various campain maps like i think helment needs full game beat on hard just to get
You unlock the armor.
go to http://hubpages.com/hub/Halo-3-Armor
You unlock the odst armor by unlocking the UNSC SPARTAN achievement
you have to get 49+ acheivments
no, well it depends on what you are talking about. E.O.D Armor is achieved by completing the Campaign on Legendary. E.O.B (employee of bungie) Is not ubtainable. This body piece is the cause of the Famous Flaming helmet.
There isn't a known cheat code for this on Halo 3.
you have to complete halo 3 odst on legendary, have xbox live and complete halo 3 on legendary
Get some skulls dummy
No, only elite's.
yes you still unlock the armor. you and the player that your playing with unlock the armor. =] =) =p q=].