Close to an offer but not sure, need advices

So I had no idea about this Wall Street Oasis site until a few days ago. Had I known, I would have done it better.

With a humanities degree and hardly any finance background, I somehow managed to get past the resume screening, then the first round interview, then the second round interviews, then the final interview with a top European IB. Call it a miracle, or a fraud, but I think it's the former. The thing is, this is a local office established in Seoul, Korea, and they might be looking for someone who is a real good bilingual, which I am.

Anyhow, because I was so ignorant of the whole IB hiring procedures and processes, I was clueless as to doing follow-up thank-you e-mails. My final round interview was done two weeks ago. I only realized this yesterday. Question #1: if you were in my shoe, would you at this point send e-mails to the interviewers who gave you business cards two weeks post factum? Would that work in my favor or against it at this stage?

Next issue. I heard back from the gentleman in charge of the hire last week that they liked me, all the folks here approved the hire, but they are waiting for an approval from the HQ in Europe, which will take around 2 weeks. Question #2. Is this a standard procedure for Korea, so removed and peripheral in the world of finance? What can be said about the likelihood of me actually getting the offer in this particular state of economy?

I would very much appreciate anyone's enlightening comments, because I am just completely clueless. For goodness' sake, I don't even know how I got this far...