The automatic tip comes out to $10 per day. This would take care of your room steward, head waiter, waiter and assistant waiter plus I believe it covers about 75 cents a day for the wait staff in the buffet.
I believe that the room steward and waiter each get $3.50 of that $10 and I think the assitant waiter gets something like $1.75 or $2.00 the rest is given to the head waiter and wait staff in the buffet. Actually most the wait staff in the buffet are the waiters and assitant waiters in the main dining rooms at night.
Room service is usually tipped when they deliver your order and most pay a $1 or $2 depending on how big an order they made.
A 15% tip will be added to every drink purchase whether soda or alcohol.
They will also tell you at the disembarkation talks what the suggested tips are.
I hope this helps some.