I'm assuming your nude beach question refers to CTI as the beach at CSS is not used for weddings. The weddings on the island occur in the evenings. The island is closed down earlier than usual (about an hour) to prepare for the wedding. The island doesn't open up again until the next day.
The new boat and new dock seem to be making a difference if the island is closed, but there are no guarantees.
I felt like the rooms at CSS were more isolated than CTI and the overall sense of the entire resort was quieter. CTI is a 'high-rise' hotel with most of the rooms in the main building. CSS has the rooms spread out in multiple buildings across the property.
Regarding your food allergies, just make arrangements to meet with the head chef upon arrival. He will discuss with you your allergies and they will be able to accommodate your needs.
Juliann & Jeff
Jamaica Soon Come