#1 A library? The internet?
#2 Search the library catalog, they're typically organized in sections based on genre and then alphabetically (by author name). Or ask a librarian for help.
#3 You'd write the call number.
#4 It's a code that tells you where items are located and tracks the book (like if somebody else has it checked out or not)
#5 Hierarchical structure or faceted classification
When a statement is only on one side and doesn't care for the other
