We had the 10 plagues, we had the Egyptians drowned in the sea, but what's the bottom-line - was Egypt at Egyptians totally ruined and the end of the story or despite the fact that some died, Egypt continued to exist normally?
This [part of the question] is purely historical/factual.
The afterthoughts for the perplexed: fighting the evil requires total extermination of it and its roots (see the story of Amalek - the war of Yehoshua or Shaul or Haman). So theoretically, fighting Egyptians (if the were The Evil) required the final solution. But on the other hand, if the Keter was exterminated there was no way of the other four Exiles. Puzzling...