We just came off that cruise (see my review in this section)
1) No problem. We had two kiddos, 13 and 11. They pulled out the futon sofa for them every night when they turned down the room and then turned it back into a sofa when they made up the room in the morning. There was a king size bed in the room for us. We were very comfortable with 4 in the room. My sister had their 20 year old and their 18 year old in their cabin, it was tight, but doable. (Mostly taking turns in the shower)
2) The Kid's Crew staff was OUTSTANDING. This was the first time my kids actually spent time in the Kid's Room. The ONLY complaint we had was that for my 11 year old, we still had to sign her in and out of the kid's crew. On Carnival, that age group could sign themselves in and out if you gave them permission to do so. But we had brought walkie talkies so she could call my wife to come sign her out when she wanted too leave, but it was still a slight hassle
3)Our cruise was during the school fall break and there were a bunch of kids on board. Our childern never had a problem with the club being "full"
4) The resturants always have hamburgers/hotdogs/chicken on the menu. The buffet always offers something too. And there is the pizza buffet. So you won't have a problem finding food the kiddos will eat. They also did not have a problem altering main selections like leaving the sauce off of a macaroni dish etc...
There you go... let me know if you want more info
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007