1. How are the szlachta unusual??
2. Elected monarchies are not peculiar to Poland.
3. Well, rather than the number of times it was partitioned, it would be more true to say that it's highly unusual for a country to disappear completely from the map and cease to be known even by its own name anymore. That is most unusual I agree - and it happened partly because of Poland's unique geographical location right in the centre of Europe between three very powerful neighbours.
4. The Battle of Vienna - what about it??