We cruised with Royal Caribbeans Navigator in October to the med and found the drinks very expensive but the pound is weak against the dollar so that makes a big difference. Yes it is a good idea to take the wine package as it does work out better.
You can take water and soft drinks on board, we did this so we could take drinks ashore. We bought a 5 bottle wine package for our 7 night cruise which was just perfect we made saving as we peferred the most expensive bottles offered in the package . We only needed to buy one extra bottle. I bought a soda package for myself and my husband drank water or the free lemonade during the day we usually had a lager/cocktail about 4pm then a pre dinner drink followed by the wine at dinner. The drinks were very reasonably priced than they are now due to the exchange rate.
Some kind person has put all the drinks menu/list on the internet. This might help you budget for drinks. http://travel.webshots.com/album/559018541CiiBCu .
The wine package 'table' will be set up in the entrance to the Windjammer, your first food stop on boarding. You can purchase there or grab a leaflet to peruse & tell the wine waiter at your table at evening meal time. If you don't finish a bottle you can have it stored till the next time or take it with you around the ship or to your cabin......wilba .