You have to preorder the game. The game will come with a slip of paper that gives you a code you can use at the main menu's downloaded content section. Once you use the code, the requirements for the outfit will be shown under outfits in single player.
You had to pre-order the game at gamestop and you got a code you can redeem on the xbox live marketplace for the deadly assassin outfit. The only way to get it now is the find one of those codes by buying it off somewhere like ebay.com
Go onto the outfit menu and you will find out what you must do to unlock that outfit.
there is no code you have 2 unlock it yourself :)
Go to the outfits menu in the pause menu and you should see what you need to do in order to unlock that outfit.
Yes, you just need to unlock it.
No. You unlock the costume by obtaining 100% sync on all story missions.
No. U need to purchase Ezio via Uplay .
Yes you can, it makes no diffeence whether you have finished the game or not.
How do you unlock the doctor outfit in which game? Please, be specific!
You can't unlock Mii outfit C.
Mii outfit C is not real. So, obviously, you can't unlock it.
You can not physically join the military in the game. The closest thing to it is the main quest line where you help Reyes overtake the Mexican Government. There are also outfits you can unlock like "The U.S Marshall Outfit" and "The American Army Outfit" But they do not put you in the military.