Laurel2 - - rest assured, I have never paid for dining on a cruise. The food in the main dining room, the buffet area and room service has always been included in our cruise fare. I do, however, tip the server for delivery with room service, just as I would in any hotel. I have paid more for beer and cocktails in some landside restaurants and bars than I've paid on board. We ALWAYS drink the ship board water. It is purified through the ship's filtration system, and is probably cleaner than what you're getting in a bottle, since there really isn't any way to tell that the bottled water isn't just run through a reverse osmosis machine before bottling. I have water bottles that have straps that we fill every day before hitting dockside. However, most lines now let you bring bottled water with you if you really think you need to have "your" brand of bottled water. I've bought a drink package once, and didn't find that it was cost effective. I can recall one 7 day cruise we did 5 years ago in which we spent less than $100 for on board drinks and souvenirs on board. We did prepay any excursions we did through the ship.
I certainly wouldn't worry about being charged for everything on board. Most dining venues are free; coffee, hot/iced tea and water are free; some lines offer an afternoon TEA service for free; entertainment is free (except the casino and some things like the Chicago or Blue Man Group and whatever goes for entertainment on some ships).
Go - Enjoy - and make your own decisions.