Since we are getting the Golden Saucer anyway sometimes in the future...

[Darkstride]

Neither did I but saw pictures. Yes as far as I know it doesn't matter what's there on the actual cards. Or at leas no value is given to them. Yet. Ace is using a Tarrot deck in Type-0. No idea what Setzer uses, but he can do mega flare with it so it's a pretty powerfull deck

Setzer used Cards, Dice and Darts (all gambling icons). Any of these that he throws deal damage, they are just themed to his character. His special ability was roulette slots (again gambling), which had nothing to do with his deck of cards. His power isn't necessarily from his weapon.... they appear to be more of a conduit for his own power (like Gambit).

I don't think there is ever an explanation as to why he has a special ability like some of the other characters, but we are talking about the SNES generation when there didn't need to be an in-depth scientific reason why he could kill monsters with playing cards.

[Snugglebutt]

They should add an ice skating rink/ice hockey perhaps in gold saucer. Skidding around on Shiva's frozen floor mechanic is quite fun.