Using the stylus tap and hold the ammunition clip. Then while the ammunition clip is held tap and hold the left corner where the ammunition is supposed to be dropped with your finger. If you now lift up the stylus the ammo clip will instantly appear where your finger is held on the touch screen. You will now be able reload by lifting up your finger.
At the 'Main' menu press X, Y, Right, Left, X. If the code has been entered correctly you will hear the sound of a zombie and the logo will turn red. ALL missions, modes, and bonuses will be unlocked and you will be able to use L and R to cycle through the camera views during gameplay.