Here are the answers to your questions:
Question 1: The Empire of Ghana was located between the Sahara Desert and major rivers.
Question 2: Mali became known in Asia, Europe, and other parts of Africa when Mansa Musa made a pilgrimage to Mecca.
Question 3: The MAIN basis for the trans-Saharan caravan trade that built the empire of Ghana was salt and gold.
Question 4: Timbuktu and Djenné became centers of learning in the Songhai Empire MAINLY due to the influence of Islam.
Question 5: The civilization that traded with India during the 1400s was the Swahili Coast.
Let me know if you have any more questions!