The soda card is $29.99 + tip which is $34.99. I was under the impression (from my first cruise) that pops were more like $3 each, so I got a card betting on having more than 10 in the week...but if it's $1.73 maybe I should re-think that. Hmm.
The soda card is a seperate card, all you have to do is show it to the bar-tender/waiter and they get your pop for you. There is a place for you to sign on the back but they never once checked it, they just glanced at it (didn't even take it from me like the Sign and Sail) so they really don't keep track of how much your getting, etc.
I have a long review of my last cruise including a bit on the Dominican if you'd like to check that out and ask any questions. It's on the Reader Reviews page under the Carnival Paradise, and my name which is Rebecca.