I am in favor of the extra spins that cost 10 or 30 electrum. An attachment to the home page that takes you to a casino wouldn't be bad either.
For blackjack, Darkness and Death could be the black suits and Fire and Entropy be the red. Shards could be jokers, rare weapons could be aces, dragons would be kings, nymphs could be queens, potions could be jacks, 2-10 could be pictures of multiple small creatures (Ash eater, lycanthrope, skeleton, parasite).
However, the electrum-for-spins would not be fair in the cases when a t50 posts a farming deck. Then you could just keep spinning and winning rare cards. I have no idea what to do about this. Please let me know if you do.