Carnival is no different than the other mass market cruise lines. Bottled water, soft drinks and alcohol are purchased (with the requisite 15% charge) on all lines. Nothing to be leery about. If you are a soda drinker, look into purchasing a soda card. If you are a water/iced tea drinker, bring along a wide-mouthed water bottle or large plastic glass for use on board. No need to be hit by "hidden" charges, if you know ahead of time that the charges exist.
The Glory does have a Supper Club. It is $25pp for the most amazing meal you will ever eat. 5-course meal. The only additional is soda, or "adult beverages." It is reservations only, which can be made from your stateroom. It is a separate intimate dinig room with live caberet style music/entertainment. There is also a live cooking demonstration of the chefs preparing your meal. Truly a wonderful experience.