Japanese Writing style?

Question:

When Japanese people write essays, poems, stories, writing prompts, comic books (manga), etc. , do they write vertical style or horizontal style?

Also, Japanese are the same as Chinese numbers (when written), correct?
Please answer both questions!

Answer:

For READING, vertical style is said to be easier, while horizontal style is more common in writing.

I've heard vertical style is better when you write to someone in formal situations. (incl. when writing an envelope) I think it's only Japanese classes that require students to write vertically in schools.