I think the answer largely depends on your geographic location. From my also layman understanding, these might count as large scale installations with documentation and stats that you can look into: Guifi[0] and NYC Mesh[1].
I'll leave the other questions to more qualified HNers :).
[0] https://en.wikipedia.org/wiki/Guifi.net
[1] https://en.wikipedia.org/wiki/NYC_Mesh