unfreezingly

I love this system, but how do you deal with the ambiguity around "ten"?

    9: nine
    A: ten?
    B: eleven
    ...
    10: ten?
    20: twenty
    30: thirty

I think your estimate for N2 is a bit too optimistic: passing it in two years would be very difficult without living in Japan.

For context, it took me 3 years of university (outside Japan) to pass N2.

For me, DuckDuckGo is second after Duck on Wikipedia (from US).

They're katakana characters, used mainly for transcribing foreign words. シ is "shi", ツ is "tsu", ン is "n" and ソ is "so".