Some of this feels inaccurate?
Overnight charging is great as your phone will charge itself slowly over the whole night, putting less strain on the battery.
On the chargers - unless they mix up wires I'm pretty sure the phone is in control of charging itself?
Powering off your phone will stop the phone using power, preserving your charge (and I guess marginally the battery)
It wasn't clear in the article - how much notice did the customers get?