The net electric field inside a dielectric decreases due to polarization. The external electric field polarizes the dielectric and an electric field is produced due to this polarization. This internal electric field will be opposite to the external electric field and therefore the net electric field inside the dielectric will be less.

for apex its: a quantum field, a gravitational field

An electric field can exist even without the presence of a magnetic field. An example of this is a stationary electric field.

The electric field gets stronger as you get closer to an electric charge.

It's the electric field.