To unlock all bonuses, use the name DoggieStyle.
Now do these achievements to activate the corresponding effect:
Cabal Boss multi-player skin: complete the Dock Yard level in Super Cop mode
Maxine multi-player skin: complete the Manson level in Super Cop mode
Multi-player skins and levels: complete story mode on the normal difficulty setting
Super Cop Mode: complete the game on normal difficulty
Infinite Ammo: complete the Train Yards in Super Cop mode
Infinite Adrenaline: complete the Back Streets level in Supper Cop mode
Incredibly Fit Dog: complete the Under Rink level in Super Cop mode
No Damage: complete the Rooftops level in Super Cop mode
Get all Weapons: complete the Villa level in Super Cop mode