Who was Tantalus and what was his wrongdoing? How was he punished? How was he story connected to the curse on the house of Atreus?

He stole Zeus' ambrosia (food or drink that gives immortality). His punishment was to be banished to a pool of water (he was made to stand in it). The problem...... if he tried to drink the pool would regress, and if he tried to reach fruit from the tree above him, the branches would move away.