In legal documents, and sometimes elsewhere, quotations are defined and emphasized by putting double commas at the beginning of every line of the quotation.
The same result may be better obtained by using smaller type, or indenting the quotation, or both.
3.

A quotation included within another quotation should be enclosed by single quotation marks.
He said: "I heard him cry 'Put down that gun,' and then I heard a shot." 4.

Titles of books, essays, art works, etc., are usually enclosed in quotation marks.

When the books are supposedly familiar to all readers, the marks are not used.

You would not print "The Bible," "Paradise Lost," "The Iliad." The titles of books, etc., are sometimes printed in italics instead of being enclosed in quotation marks.