(A) Do you OK?
(B) Do you agree?

Are (A) & (B) alike?

(A) Do you OK?
(B) Do you agree?

(A) is not good English. You could say , "Do you think that's OK?" but that would be more like asking if something is acceptable and wouldn't necessarily imply that the person asked agreed. You could also say, "Can you OK this?" which would mean that you are asking for permission. Neither would be the same as (B).

Dear soojin: OK is most often used in a reply, to indicate comprehension, agreement, willingness to comply, and correctness. It is fine informal things such as memos, but may not be suitable in reports or proposals.
In your examples B is the more suitable.

Dear Max Quordlepleen, Faldage, wwh,

I see.
Thank you very much.