How does the difference in the salutations $($the "Dear..." part of the letter$)$ reflect a cultural difference?

Does the first paragraph of the second letter have any function beyond delaying the discussion of business?

What is the point of telling Mr$.$ Kirisawa about his own company? How does this paragraph help the writer introduce her own company's products?

To a reader from the United States, the third paragraph of the second letter would probably seem thin. What aspect of Japanese culture makes it effective in the context of this letter?

Why doesn't the writer make a more explicit sales pitch at the end of the second letter?