Hooks should be barbless, missing the little point on the back of the hook. Serious fishermen prefer the barb, but it's far too risky for children.
The hook size is dependent on the size of the bait you are using. Bring extras, as you know there might be a few snags along the way. For freshwater spots, you don't need a hook larger than a 10. (Hook sizes descend; a 12 is smaller than a 10.)