I'm also wondering how commute time (and method of commute) factors into this. Does 30 minutes of physically strenuous cycling before/after work have a positive or negative impact on office workers? Does the same time spent in a car navigating stop'n'go traffic have a different effect? Both involve some element of mental effort, but both are quite different from the rest of the days tasks. Certainly in my experience one helped my mental state and one didn't.
Anecdotally, I once moved from having an hour long commute to a 5 minutes walk from work. I did end up leaving, but I feel that I enjoyed life much more living close to the office. Getting an extra two hours every day allowed me to enjoy life much more.
Absolutely. I'm at least as convinced that 35 hours is optimal time as I am that 45 is. I also agree with your point about commutes. Instead of looking at time in the office it probably makes more sense to look at the time from when one leaves home to when one leaves the office. And speaking only for myself, having to drive 30 minutes to work each morning would be a pretty major deal-breaker for any job I'd consider.
That was true when most of the workforce was doing manual and factory style labour. To the best of my knowledge it hasn't been rigorously reproduced for works that spend their days staring at a screen thinking.