Questions on Hatching Crocs

Why did the crocodile have to add sand on top of the nests in the game?

to keep her baby's in a nice temperate. 

If a mother crocodile wanted to hatch only male babies or female babies, what would she do?

She has to get the right temperate for her eggs to be able to get only boys or only girls.

What does the mother crocodile do after she lays her eggs?

she has to add some dirt to get the crocodiles at the right temperate.

What animals are predators (hunters) of the crocodile eggs? What did they do to get the eggs?

other crocodiles,raccoons.  The predators dig the dirt to get to the eggs.