After the implant, The mapping is covered but for everything else, even an processor upgrade, you are more likely have to pay out of your pocket. I am trying to see if my rechargable battery will be covered by my insurance, but I have a feeling it won't.
Anyway, if your child have implant as a baby, don't be afraid to use ASL (especially if you think he will develop language skills like a hearing baby... baby sign never affected hearing babies at all so I don't see the harm of ASL)