Download the Carnival Hub App before you board. Once on the ship login, put phone on airplane mode, and connect to the ship wifi. You can view your account balance as well as a breakdown of where each purchase was made and for how much.
In 24 Carnival cruises we had never been to the steakhouse until our last cruise on the Magic this past October. I wish we didn't go this time. Terrible cut of meat. Worst we have had at sea or maybe anywhere for that matter. Slow inattentive service. I wrote Carnival but never heard anything back. They got us once but never again.
We found the MDR to be pretty good. The buffet was terrible. From cold to stale. You name it. The Steakhouse awful. Worst cuts of meat, not cooked right, terrible service.
I have seen both police and city parking authorities monitoring the garages. YMMV. I am just relaying our experiences and what we have seen. You may be able to get by with it by parking there the night before. There is a garage directly across from the entrance to Half Moone. About a 2 minute walk.
I am unaware of any that provide shuttle. The closest hotels to the port are the Marriott and Hilton on Main. There is also a Sheraton a little bit further down Waterside drive.
In the past we were lucky enough to park there for a cruise. The past two years they block off all city owned garages to cruisers and you will not be allowed to park there.
We finally went recently on the Magic to the Steakhouse for the very first time after 22 cruises. It was the worst experience ever. From the inattentive service to the worst cuts of steak possible it was all terrible. They got our $84 but never again.
You will be able to select your check-in time at midnight EST. For our last cruise I set my alarm to wake up a few minutes prior. Just kept refreshing my screen till it showed up.
My experience is that the entrance will be monitored, blocked off, and they will not allow you to park in that parking garage for the cruise. It would be so convenient being it is right across the street.