Yes. Our 15 month old was on our first 14-night transatlantic crossing with Disney. Also, if you are booking with a rate that includes prepaying gratuities, then the infants are included with prepaid gratuities.
Even for the Servers? I'm not trying to be cheap or anything, but why would I tip the servers for an infant? I'm the one serving the baby.. Lol At most the only thing we would need from the servers is an extra chair to set the car seat in, and if I bring the baby in a sling we wouldn't even need that.
I would include the baby for tips for the room steward because they would also have to set up the pack n play every night and take it down every morning, empty the dirty diapers, etc. He'll probably get extra for the baby.
I just don't get the servers and why I'm tipping them, for the baby.