I don't know the sock size either. So if you are reading this and didn't post a sock size, please do! I figured I'd just send medium and hope for the best. If it's wrong, then hopefully they'll say something so I can get it right the next time!

Yes, customs forms are required for out of country items. Just make sure you mark it as a gift! I lived overseas twice, and it's a pain making out forms for all the Christmas presents. I got good at consolidating gifts--send to parents and ask them to distribute to brothers/sisters who lived in same city.