Don't worry..there will be PLENTY of kids on board. I have a 14 year old and we were on the Pride last summer. She had a BLAST. She spent a lot of time with her new friends in Circle C. They do have parties in the evening which do last until 12.30 or so..be prepared! I would go occasionally and check in to see what she was up to...mostly they were all just hanging out, playing games and socializing. We would make her come and find us (we would let her know what our plans were) to let us know if she was doing something other than hanging out in the club. All was well.
As far as when it gets warm..well by your second day you should not have any problems with it being cold (though it does get breezy on deck) Of course with our nasty weather in the mid-atlantic this month..who knows!! We need spring for sure!
Have a fabulous time. The staff was wonderful..especially the girl in the coffee shop (if she is still there). She was so sweet and friendly.