How high is Mt. Everest?

It is 8,848 meters high.

How tall is Mt. Everest?
It is 8,848 meters tall.

(Are both questions and answers correct?)

1. How high Mt. Everest is!
Yes, it is.
Yes, it really is.
Yes, you are right.

Are the responses all right?
Would you let me know more suitable responses?

2. It is 8,488 m high.
3. It is 8,488 ms high.

(Are both correct?)

4. What a pretty girl she is!
5. How pretty a girl she is!
6. How pretty she is!

(Among the three, which one is not correct? Is #5 correct?)

7. She is so pretty a girl.
8. She is such a pretty girl.
(Are both grammatical?)

2 answers

How high is Mt. Everest?
It is 8,848 meters high.

How tall is Mt. Everest?
It is 8,848 meters tall.

(Are both questions and answers correct?)
Both are correct, but the first is better than the second.

1. How high Mt. Everest is!
Yes, it is.
Yes, it really is.
Yes, you are right.

Are the responses all right?
Would you let me know more suitable responses?
Yes, all are fine. You could also respond, "It certainly is." or "It sure is!"

2. It is 8,488 m high.
3. It is 8,488 ms high.

(Are both correct?)
I have seen m as the abbreviation for meter or meters, but not ms.

4. What a pretty girl she is!
5. How pretty a girl she is!
6. How pretty she is!

(Among the three, which one is not correct? Is #5 correct?)
4 and 6 are best; 5 is awkward and not used.

7. She is so pretty a girl.
8. She is such a pretty girl.
(Are both grammatical?)
8 is find, but not 7.
Should be "fine" not "find"!!