Small wonder you have these questions. I just checked the FAQ for Celebrity Cruises and found it less than helpful. The FAQ for Carnival Cruises is considerably more detailed and helpful. What is clear to me from what I have read and from what has been said above is that there are many differences among cruise lines with regard to what can or cannot be brought aboard. Carnival, for instance, does not allow medical marijuana, musical instruments, (unless you are a scheduled performer,) and no alcoholic beverages (sealed or unsealed) other than a limited amount of wine. Carnival's FAQ does contain a valuable breakdown of how much to tip who. Here is what they have to say:

Service Gratuities

For your convenience, we automatically charge the gratuities for dining and stateroom staff to your onboard Sail & Sign account. The total amount is $10.00 per guest, per day (our recommended guideline) as follows:

$ 3.50 Per Day Stateroom Services            

$ 5.50 Per Day Dining Room Services      

$ 1.00 Per Day Alternative Services: distributed to other kitchen and hotel service staff

For Cruises-To-Nowhere, gratuities of $10 per guest, per day must be prepaid.

Our Staff is totally committed to exceed your expectations in every way possible. If you are not satisfied with the service you receive, we encourage you to contact the Guest Services desk while onboard. This will allow us to address your concerns in a timely and appropriate fashion. At your discretion, you may adjust the gratuities at any time while onboard. Gratuities will be deemed undisputed unless a request to modify is received prior to disembarking the ship.

For beverage purchases, fifteen percent of the bill is automatically added to the Sail & Sign charge. Room Service staff may be tipped as service is rendered. Tipping your Maître d' is at your discretion, based upon the service you receive.

NOTE: BARBADOS CRUISES
All gratuities are pre-paid and automatically added during the booking process for Barbados itineraries.