You know, I don't think I've ever run into someone who wanted to bring food onto a ship. =huh I had to stop to think: why on earth...?
My first thought was that you might as well bring along a little extra seawater for the ocean. Second thought is that, you must have allergies or some health issues that require a special diet ? Is that it? They do ask you about special dietary needs when you book, and they try to accomodate them . At least I've seen them provide specially prepared food for a diabetic at our table.
If that's not it, trust me, you will NOT go hungry !
As for bringing drinks: yes true about bringing the bottle of wine. Lots of people do. As reasonable amount, like a 12 pack, of soda is usually OK too. Liquor is not supposed to be brought on, but I hear lots of talk from reliable sources about people doing it. We don't. It's not worth the effort involved. IMHO