The Devshirme system was a system where Christian boys were recruited by force to serve the Ottoman government.
While you didn't really provide the "following" as the comment above me states, in general, the advantage of secondary sources of primary ones is that they perhaps provide a more objective or even just a broader view on a certain topic. While a primary source of the American civil war would be a letter written by a soldier, a secondary source would be a book that describes more letters taken together and discusses possible information regarding them.
It allowed them to make their own laws separately from Britian.
It was the internal reforms of Mikhail Gorbachev, the last Soviet leader that led to the end of the Cold War
