This seems to me a whole lot of stuff about something that really isn't
very difficult.
The displacement "current" is nothing more than a time varying electric
field. It is called a "current", even though it doesn't involved moving
charges, because it generates a magnetic field exactly as does a "real"
current (that is, moving charges). In fact dE/dt just adds to the usual
current in Maxwell's equations.
This is not a mere curiosity. Without the displacement current there
would be no electromagnetic waves in the vacuum, i.e. no such thing as
light.