Nitration Of Methyl Benzoate

1) why were crystals formed washed with water before recrystallisation?

2) what happens during recrystillisation to:
a) impurities
b) the main product

3) how is the loss of the product kept to a minium during recrystallisation?

4) what are the usual stages in the purification of an organic solid?

very urgent !!! thanks alot !!!!