So is there any evidence that the local power company has been able to back off generation of reliably-sourced electricity in any kind of equivalent amount to this “clean green electricity” or even that it’s realistically integrated into the grid?
Different site, but you may want to look at the data from We power. Many of the sites listed show active live and historic power data.
http://www.we-energies.com/residential/energyeff/active_installdata.htm
No. Utilities still have to provide a base of production capacity. Solar and wind cannot provide that due to the transient nature of wind and sunlight.