Patticake..........we never activate our kids cards for charging purposes as there's really nothing they need to buy on the ship and it's one less thing to worry about. One of my sons did lose his card and went to the purser's office to get a new one. As it wasn't activated, we didn't have to worry about somebody using his card to buy something.
On another note, I see you are presenting information to a group. I, too, am going with a group, but once the initial information was given to them, I've let them find out things on their own (of course, I'm always available if they need something). Just a thought, but I would try to get them more involved so everything isn't up to you. Encourage them to visit Carnival.com..............there is so much information in the Frequently Asked Questions (FAQ's) section. They will also need to know how to navigate that sight to fill out their fun passes. You can also let them know about sites like this so they can ask their own questions.