I parasailed with my 8 /o daughter back in December at CC, and I recall the minimum weight being posted as 80 lbs. However, when I purchased the tickets at the shore excursion desk on board, the CM told me that my 70 lb. daughter would be fine since she was going with me. He indicated that the 80 lb. minimum was for solo parasailing. When you get to the dock to get on your parasail boat, there is no scale or anything. So I tend to think that your husband would have to go up 2 seperate times, once with your daughter and once with your son. Cameras are fine, people in the boat can take your pic from the boat as you go up or take the camera with you since you "sit" in a harness.
No matter which way you go with this, I have to say definitely do the Banana Boating as a family. Our whole family had a blast with this, as a matter of fact it was such a blast that we did it twice (relatively inexpensive at $14 each compared to the cost of parasailing). One note of caution, if you sit in either of the front 2 positions of the boat you will get several mouthfuls of salt water splast, and into your eyes as well. Since someone had warned us of this, we had a pair of Speedo goggles with us for my 7 y/o son to wear, and he sat in the front next to me. Despite the salty spray (and note that the water down there is alot saltier than the mid-atlantic ocean, it was absolutely awesome.
Enjoy!!!!!!!!!!!!!!!!