I would estimate this as about 85 people, or 7/8 of 100. This menu plan is a little lean for this size crowd, and for this long of a party I would also suggest you need some appetizer/ nibble plans.
Meat is OK, but if that is raw weight on the pork, there won't be much left.
Rice- most adults take 3/4 cup, you might want to increase.
Mango salad- OK, none left- you might add a kid friendly one- a couple of gallons of carrot raisin, Waldorf, or Frog Eye (pasta and fruit).
Some kind of bread or roll?
Now for the extras; with people at the beach, you are going to want cool and wet as well as crunchy and salty. What about chips and dips? 2 ounces chips plus 1/4-1/3 cup dip per person. Watermelons iced for cutting, at least 1 pound per 3-4.
Also, beverages, you need about double what I usually recommend on the beverage page, to cover the whole day- it is really 2 events. You MUST have some sugar free choices.
For the hot food transport, see the information on the potato bar page for how to heat and transfer hot potatoes. You need the rigid containers, they need to be preheated, the food needs to go in HOT, the containers are full (in other words, use smaller ones, rather that larger and open just what you need) and you keep them closed until ready to serve- food cannot sit out more that 1-2 hours in beach heat, and if you keep opening and closing a container, the temp rapidly drops to unsafe levels.