To unlock all campaigns, you have to edit the "game.dat" file (find it in the game directory) and locate the line "Volume: -750, 0, -5??" and change it to "Volume: -750, 0, -581".
To get $10,000, enter "Columbus" and give yourself a yellow flag for $10,000.
To get free items, when you buy something and your income is low, save the game and load it again to get your money back.