Is it I may be wrong or I might be wrong?
I might have been wrong you are saying you were probably wrong in a situation that has happened. I may have been wrong is using the present/future perfect tense. simply saying you were probably wrong about a situation that has started in the past but is still continuing.
Is it I stand corrected or I stand to be corrected?
I stand corrected is usually the more common expression. I stand to be corrected. means this according to a person on this forum: Its a quick way of saying I might be wrong about that statement I have just made and feel sure somebody will put me right if that is the case.