No, that's not correct. I think they charge for Johnny Rockets, which is a 1950's style burger place, but there are free burgers elsewhere.
They also charge for the specialty restaurant, a fancy place you have to make reservations for. That's about it. Everything else is included in your cruise price.
The only other thing I can think of is tipping. That's the $10 per day per person suggestion. Sometimes it's added to your charge card and people have discussed this in the general cruise chat section.
I forgot something. You do have to pay for soda cards, but they're for unlimited fountain cokes. There is free tea, coffee, lemonade, and water. I would caution your children not to drink the canned cokes in the fridge because you'll be charged for them. I think it's something like $1.50 a can, which sometimes is worth it. I always buy cokes at the various ports and they've never stopped me from bringing them on the ship.
There is a coffee bar, kind of like Starbucks and that coffee isn't free. Regular coffee at the restaurants and buffet is free.
As far as I can remember, ice cream is free. At least the stuff near the buffet is.
I remember free soft serve ice cream on the Explorer last summer. There was a surcharge for Johnny Rockets, I think it was $3.95, I could be mistaken. But, boy was it yummy, and a fun place to eat at. There are music juke boxes at each table. They take quarters, if I remember correctly. Have fun and enjoy, Lil' Lori
Just come off the Explorer and there was free frozen yoghurt style ice cream available by the main pool all day every day! The cover charge only applies to Johnny Rockets which had great food, but with plenty of really good food available elsewhere on the ship, there is no need to pay extra if you don't want.
I thought about your question some more. You can take a cruise and spend about zero on board the ship. Some people enjoy the extra perks and are willing to pay for them... wine at dinner, specialty restaurants, massages, drinks by the pool, casino, and all the rest. But you absolutely can have a stupendous time and not partake in any of that. I think we charge less than $60 a cruise and most of it is for cokes, ship t-shirts, and special coffee.
You'll know when something costs extra because they'll ask for your room key/charge card/identification card.
I think I read somewhere that when you check in and show them your credit card, you can keep the kids' cards from being used as charge cards.