The quiet environment I was describing can be found in an office where the majority of people are heads-down working and not on the phone. This is harder to find when you're in an office that's setup as a cube-farm or an open layout. But this can be easily found at the beginning or end of the day and especially on work days that bookend holidays or three day weekends - days that lots of people typically take vacation. Those are the times when I find I get my best work done because it is the closest to quiet and distraction-free that one can find, other than working remotely where you can control the environment.
As far as the "go-to" person people have noted having above, everyone on my team works on different aspects of what we do, so no one person can answer every question. Our PM is also not super familiar with what those roles are nor are they technically competent enough to answer those questions on their own (as of now, anyway).