Yes, the Americans cracked the code before Midway but then the Japanese changed the code again.
I think that was a constant game of catch up.
On average, the second world war claim 35,000 lives a day.
Killing 100,000 people in one go obviously sounds horrendous now but not compared to what was happening every day.
Ask almost any American at the time to choose between 1,000 dead Japanese or 1 dead American - and I think you know how they would answer.
The Russians got involved because the Americans ask them to get involved.
Bizarrely, if the Japanese had surrendered a week earlier before the Russians got involved (exactly 3 months after the surrender of Germany) then it is possible that Korea would not have been partitioned and we not have this crisis today.
Purely "what if" I know but interesting.