(1) Saturdays are the most borrowed for tourism and the least for literature and art;

(2) Life books are borrowed the most on Sundays, while literature books are the least;

(3) Because 180÷90=2, the borrowing volume of science and technology books on Saturday is twice that of literature and art books;

(4) Question 1: How much more books are borrowed on Sunday than on Saturday?

145-90=55 (Ben);

A: There are 55 more books borrowed on Sunday than on Saturday.

Question 2: How many science and technology books do you borrow on Saturday and Sunday?

180+ 160=340 (Ben);

A: On Saturday and Sunday, 340 scientific and technological books were lent out.

So the answer is: tourism, literature and art, life, literature and art, 6. Science and technology, literature and art.