But "estén" also has its role under the right circumstances. "We met that evening" is translated as "Azon az estén találkoztunk". So, maybe, when it is a this/that kind of evening.
No! "In the evening" is after most people have finished work but before they have gone to bed. "At night" is when it is dark and most people are in bed. However, "tonight" is often used when we really mean "this evening".