We usually book our own air transportation so I can't help you there.
We often go in the day before...in San Juan we stay at a hotel half way between the airport and the pier (cheaper). So we taxi to both the hotel and the port. You can take the transporation to the ship that Carnival offers....it's not a horrible deal..usually just a tad below taxi cost. (When we take the Carnival bus from the airport to the port - we stay at a hotel close to the airport...with shuttle service. Still coming in the day before but heading back to the airport in the AM to catch the bus.) This may be a mute point if you are coming in the same day. Since the ship leaves so late in the day that may work out just fine for you. You can board the ship inbetween 12 and 1..depending on how early the previous guests managed to disembark. You can also disembark and tour old san Juan after you have checked in....provided it's not too close to sailing time.
The reason they suggest tipping the porters is that they are not Carnival employees.
I saw your post on the cabin first...so I didn't know you were traveling alone. There should be plenty of room for just one person..even if you think it's not you won't be spending much time there anyway.
We thought the ports really made this trip exceptional. If you take a Carnival excursion you may want to tip your guide and your bus driver.
The bottled water or pop in the room is not free. Soda Pop is never free. Regular water (they have pretty good purification systems, I've not gotten sick on the water), punch, coffee, tea (hot or cold), juice and sometimes hot chocolate can always be obtained on the Lido Deck and is free. Ice cream and pizza are also available 24/7 for free (so to speak - at no extra charge.) If you want expresso, other specialized coffees and/or special deserts there is a bar containing these for an extra charge. There is a 15% automatic gratuity for everything from the bar (including pop). There is a shushi bar but it's usually only open an hour or so before dinner...check for the times in your Carnival Caper.
The Carnival Caper is a paper you will receive daily containing the next days activities. Who's singing where, what to wear for dinner, which port you will be at, whether to change your clock or not...etc. I use to write down everything we thought we might like to do on a piece of paper so I didn't have to take the whole Caper with me....now there's a portion that is perferated so I don't have to do that.
Liquor will be kept for you until the day before you leave...with the possible exception of what you smuggle on in your suitcase. When you purchase any liquor in port the ship will ask to have it until later. Be aware that you won't be able to take anything back on the plane unless you want to risk a bottle not breaking in your checked luggage.
When you check in you will be given a "sail and sign" card. It will be your room key (no cabin number on it) and also your "credit card" while on board ship. At the end of the cruise you will get a statement of what you spent while using your sail and sign card. The tips will be placed on the S&S card when you check in. If you want them changed one way or another you can do so at the Purser's Desk. We usually take extra cash for tipping extra - if the service we get goes above and beyond the norm. If I remember correctly there is also a %fee if you use your S&S card in the casino. So you may want cash or travelers checks for that.
You will have a safe in your room...it works by magnetic strip. They suggest you not use your sail and sign card since someone has a master key. I usually take an old credit card - one I cancelled - and use it. (It doesn't have to be an old one...just any card with a magnetic strip.)
I can't think of anything else at the moment...it's getting late here. If you think of a particular question you want to ask me...please do so by using the "reply by PM" at the bottom of this post. I don't always remember to recheck my posts and this will give me a message when I log on so I know I have a personal message.
