When is the first meeting?

1. It is at nine this Saturday.
2. It is nine this Saturday.

(Which answer is right?)

When is the next meeting?
3. It is on April 3, 9:00 a.m.
4. It is April 3, 9:00 a.m.
4-1. It is at 9:00 a.m., April 3.
4-2. It is 9 a.m., April 3rd.
(Are the answers all correct?)

Who is the speaker?
5. Yun Seho. He is the president of the cooking club, Yummy.

6. He is Yun Seho, who is the speaker of the cooking club, Yummy.

7. Yun Seho, the president of the cooking club, Yummy.

8. He is Yun Seho, the president of the cooking club, Yummy.

(Are the answers all correct?)

#1 is correct. #2 is not incorrect, just not used much. (I've never heard it!)

3&4 are all fine.

5-8 are all correct, but #6 is rather formal, and not used much.