now that all the information is on the table, walkie talkie is the best way to go...just be sure hubby is in the casino (where it is noisy) and you're calling him from an equally noisy place...like the engine room! have a really nice cruise.
I am not big on either but the walkie talkies would probably be better.
As far as the credit card and money goes on the ship your room key will be your credit card on the ship. No cash needed unless you want to use cash in the casino.