Coordinating conjunction to join independent questions

When a coordinating conjunction joins two independent clauses, a comma is used before the coordinating conjunction(unless the two independent clauses are very short).

Do the same rules apply when coordinating conjunctions are used to join two independent questions?

Who is being introduced, and what does he do?

Who is the person, and why was he chosen?

Is it grammatically correct to write the sentences without the comma?

Who is being introduced and what does he do?

Who is the person and why was he chosen?

Which one is more appropriate in formal writing?