I would dispute question 2. With over 2.7m foreign nationals, 1m plus Okinawans, Ainu, mixed race, and naturalized citizens, I think 98% is wrong. However the Japanese government doesn't survey its citizens for ethnicity hence why you have the erroneous figure of 98%
I completely agree with this dispute, but sadly I think it's hard to tell because of how they classify ethnicity. But yeah, there's no way it's over 98% because during the Meiji period, they reclassified Ryuukyuuans as Yamato.
So did I :D and also question 7. "So the Mongols came over, ready for war, and died in a tornado. But they tried again and had a nice time fighting with the Japanese, but then died in a tornado." Thank you Bill!
As a Japanese person I got the emperor question wrong because deceased emperors are most commonly referred to by [era name] Emperor or Showa Emperor in this case