We are going on the Carnival freedom. I do know there is baby sitting. I did not know if they babysit while you are off the ship. On the excursion there is no age on it.
Let's start with the babysitting. Camp Carnival offers participation in the program for 3 year olds on port days.
The child prices listed on the Shore Excursions are for 4 - 12 year olds. If the excursion shows a "Baby Bottle" icon (this one doesn't) that means an infant can go for free as long as they don't occupy a seat. I don't know how strict they are with this.