To answer your question: "What are the limitations for using shape water for cheating and forgery?" the limitations are:
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 - Maintaining line of sight and a clear path to the water

 - Having water available to manipulate and not a dry color.

 - Being able to somehow hide your spellcasting from those that could discern what you are doing.

 - Following a strict adherence to the allowed uses of the spell enumerated in its description.

Your uses of shape water are imaginative, though I imagine one does not roll dice or play cards with wet surfaces. 

Consider that you shape water with that spell, not evaporated colors; are your play surfaces still damp?

Also, consider that spells are not necessarily subtle, unless you are using the sorcerer class ability. This would imply there is a good chance that someone will be on to you and your cheating.

You also would have to cast this spell, presumably, more than once to continue to manipulate the water (frost, what have you) to your liking.