As to sand toys, it is only a chance that someone will leave them. To be on the safe side I would pack your own. When my dd was younger I would put her toys in the suitcase and stuff things like socks and undies in the little pail to at least conserve some space.
If you wish to buy them there, your best bet would probably to walk to Hong King or Certified supermarket to pick them up. The sundries shop at the resort sells toys as well, but I would venture to guess they are going to be more expensive that what you could get at home.
Baby Beach -just to be lazy and float on my raft and snorkle too
I would bring the beach toys, pail, shovel, and a float too. You can check the activities center and you might find a noodle for the pool or ocean and sometimes beach stuff and other times none. We always leave ours at the end of our trip becuase we bought so much to take back.
Remember to bring some books, crayons, coloring books, etc to keep her busy at dinner time.