So does this mean they are going back and updating old imagery? My neighborhood (in a small city) hasn't been updated since 2011, and quite a few areas have street views that don't match reality anymore
Looks like streetview of center of Helsinki was last updated 2009. Granted it's not very big either but capital of a european country still.
I think that's what they are doing with the live view street directions. They can easily recreate the new imagery based on the users photos.
I very much doubt it. The entire point of that is to gauge the location of the user based on the existing street view imagery. Perhaps they'll add something eventually where users can contribute imagery from their phones, but I think that feature won't be the way to do it.
They already have user contributed imagery. In parks, Google usually maps the paths but you can see dots
off the paths for user added points.
Looks extremely simple for anyone to do this for google now, so I'd guess yes
That has been happening all along, but I would expect not everywhere.