1. Bestbuy.com They store date about their products price, reviews and availability. 
   FiFA.com They store information about all soccer players around the world. They store dates of birth, stats, nationality, and all information about their club teams and their national teams.

2&3. department 1------ Many professor 1 ------ Many course Many ------ Many classroom.

4.CD title, Artist, Music type, Release date, Single or Group, 

5. Tables include the whole range of data.  Query results are a specific part of all that data.  The data in the query results in manipulated by your limits of the same.