Reading Megillah Remotely

This supplement deals with the following three questions, of special import during Covid-19:

May one fulfill the obligation of reading the megillah on Purim by phone or online?
If it is indeed not necessary for listeners to be physically present for the reading of the megillah (so long as they can hear it with technological assistance), can the same be true for the readers of the megillah?
If there is no minyan present where the megillah is being read, can a remote audience count toward a minyan for the purposes of reciting the special blessing—הרב את ריבנו—which is normally only recited in the presence of a minyan?