Hi All!
I say order whatever you want, but eat what you take (echoing the don't be wasteful vibe

, and if you run your servers legs off asking for extras be sure to tip accordingly.
It isn't rude as they plan for it and the fresh food that is brought aboard but unused at the end of the trip will be discarded before the next sailing. Likewise, any meals plated or food prepared but unserved won't be making another appearance at the table ( I seem to remember from taking the kitchen tour that it might be made available to the staff after the meal period but can't be sure.)
On our first
Disney cruise to Mexico in '05 the DH was so excited about getting lobster in an upcoming meal (He loves him some dead sea bug!) that he mentioned it at the table on the first night within (unknowingly) earshot of our server Clive. On Captain's Gala night we arrived at dinner to find two lobster tails on each of our plates. The rest of our group was sure surprised.
I also use the menu to try new things reasoning that if they do it well, and I don't become a fan then I just might not like it period. I tried escargot, the garlic and butter was nice (isn't it always?) but otherwise it was nothing special.
Enjoy your vacation. The fun... The food... But most of all... The experience!
Take care all, help lots of people and have a "Wonder"ful day!
Tisza