Recommend you ask this on the forum for whatever cruise line you are sailing on since there are different alcohol policies on each line. I highly doubt though, that any of them allow third party alcohol deliveries.
Welcome to Cruise Critic.
From NCL's FAQ's.
What not to bring onboard
Passengers should not bring the following items onboard any Norwegian Cruise Line ship:
Drones (Game Flying Device)
Guests are not permitted to bring drones onboard for safety of other guests, as well as the welfare of the vessel.
There's a whole forum on Cruise/Travel insurance with lots of great info. Here's the link for you:
https://boards.cruisecritic.com/forum/499-cruisetravel-insurance/
The legality of dormancy fees vary by state. If you Google something like "gift card dormancy fees by state" you should find what applies to you. Good luck.
Recommend you ask on the RCI forum for issues specific to that line. Here is the link for you:
https://boards.cruisecritic.com/forum/51-royal-caribbean-international/
I would go ahead and plan your specialty venue dining, you can always cancel later on. To be honest anymore I can't really think of anything "great" that you would miss in the MDR's.
Enjoy and welcome to CC.