Painting and decorating paper mache?

i've made a paper mache island for my little boys playmobil pirate ship, pirates, skeletons, treasure etc, and i now need to know which paint is best to paint it with, acrylic or poster paint? also, i was wondering if adding real sand to the beach part of the island would be possible by mixing it in with the paint, then painting on or would this not work? would it just come off when my son starts playing with his toys on it? thanks in advance