1. What are the characters of Dokdo?
- They are Dokdorang.
(Dokdorang is composed of two island images. Is the question and the answer correct?)
2. What will they be today?
3. What will they do today?
- They will be our tour guides today. (Which quetion is suitable for the answer?)
4. How far is Ulleongdo from Dokdo?
-It is 87.4 km away from Dokdo.
(Is the question and the answer correct?)
5. How far is it from Ulleongdo to Dokdo?
-It is 87.4 km away from Ulleongdo to Dokdo?
(Is the question and the answer correct?)
1. I think you mean "characteristics," not "characters."
2 is the question for that answer. For 3, the answer would be, "They will guide us around the city today."
4. All is correct, yes.
5. I'd remove "away" and the answer will be correct.