Questions unanswered by the final...

a) Who banged Toph?

b) Where is Zuko's mom?

c) Iroh II's father?

Obviously no one knows the answer to b or c, but do we have any clue what the answer is to question a and what other major questions am I not thinking about?

(I don't think this belongs in the episode discussion thread because it's not really related to the final)