Why was the Black Stone given this name? Is there a document inside it, and what is in this document if it exists?

The naming of the "Most Fortunate Stone" (الحجر الأسعد) has not been mentioned in the texts of revelation or in the books of the ancients. Rather, what is known is the Black Stone (الحجر الأسود). As for the document, it contains a very weak narration attributed to Ali ibn Abi Talib, stating that Allah took the covenants and pledges of the Children of Adam and wrote them on a parchment, and that parchment was then placed into the Stone. This hadith has been deemed weak by Ibn Hajar, Al-Suyuti, and Al-Shawkani due to the presence of a very weak narrator in its chain of transmission.