I answered your question on X1 package on 10th may but forgot to add bottled beer is also included.
I think it would help if you said when you are going as it will make the answer easier and more accurate. I also hope that you are not going through Norway because that could be very bumpy ... sorry ...Nei.
Our trip is in August ny positive advice.
Yes you will find that the weather and the conditions at sea will be very similar to British summer conditions provided you do not get a gale and the sea conditions in the Fjords will be pancake flat. Never been on or intend to go on Costa so can't help with the rest. The main difference is that it stays light almost throughout the night ...regards Nei.
You can buy a wine and water package through the costa site or buy an X1 package which includes bottled water, fizzy juice red and white wine during meal times in main resturant and all buffet resturants when meals are being served. you receive 2 drinks per card. this has to be bought through your travel agent and paid befor you travel. for 11 nights in feb 08 it cost £83 per card. we only bought one card. hope this helps.