I am curious as to what happened to Greece afterwards. Most of Hellas was in the Delian and Peloponnesian League at the end. What happened to them? I know the Spartan's used "we will liberate Hellas" as a way to gain support for the war on Athens but did they really? All they did was create an oligarchy which was disbanded in a year anyways when Athens took back control.
Athens never really regained their empire after "the Thirty" (the oligarchy) was established by the Spartans. The Athenian empire and the Peloponnesian league were still pretty abstract concepts, the liberation your implying wasn't a hugely dramatic event. Athens stopped collecting tribute and ships from their "allies", the ex-Delian League. The states that had become democratic often reverted to being oligarchic, but that was a natural regression rather than a liberation. The Peloponnesian League was an even less regulated body, more just strategic meetings between Sparta, Corinth et. al.
With reference to your second question, Athens could never really regained control of their empire without the financial capital that its navy required. Greece therefore reverted back to type, having smaller scale wars between city-states, Thebes became the major player, defeating Sparta at Leuctra in 379. Then Philip of Macedon (Alexander's dad) came down and smushed them all.