Various cheats:
RAIN SNOWMEN:
In Horrorland Plaza click the moon, then the brown patch next to a tree.

BONUS GAME:
In Horrorland Plaza look in the bins until you find a hammer. Go back to Werewolf Village and hit the worm at the gas tanks. You will now be able to play a hit-the-worm game.

SPRAY PAINT:

In Vampire Village click on the wall opposite the stained glass windows.

BLOOD BANK:

Either get the card from the Werewolf's house and enter the number into the bank.