electromagnetism - How are forces "mediated"?

I hope this is the right word to use.

To me, these forces seem kind of fanciful (except for General Relativity and Gravity, which have a geometric interpretation).

For example, how do two charged particles know that they are to move apart from each other?

Do they communicate with each other somehow through some means?

I've heard some people tell me that they bounce together messenger photons. So does one electron receive a messenger photon, go, "Oh hey, I should move in the direction opposite of where this came from, due to the data in it", and then move?

Aren't photons also associated with energy, as well? Does this type of mediation imply that electrons give off energy in order to exert force on other electrons?

Every electron is repelled by every other electron in the universe, right? How does it know where to send its force mediators? Does it just know what direction to point it in? Does it simply send it in all directions in a continuum? Does that mean it's always giving off photons/energy?

I'm just not sure how to view "how" it is that electrons know they are to move away from each other.

These questions have always bugged me when studying forces. I'm sure the Standard Model has something to shed some light on it.

Answer

Brief answer: Read only the bold part (and ignore grammar then).

The answer you already mentioned lies in Quantum Field Theory (QFT). But to fully understand it, you must give up a particle as a point-like thing that is well-localized. There is one Quantum Field per sort of particle, e.g. the electron field for all electrons, and the photon field for all photons. (The fact that there is a single field for all electrons also results in the Pauli exclusion principle.)

What you consider a particle is basically just a local peak in the respective particle field, but one cannot even say "This peak corresponds to electron A, this one to B". Now QFT, more specifically Quantum Electrodynamcis (QED), describes the local interaction between the electron field and the photon field. But since the fields have a dynamic, a local change induced in the photon field by the electron field will propagate with the speed of light (flat space assumed) and interact with the electron field in another place, thus creating the impression "Electron A emitted a photon that told electron B to interact electromagnetically".

It's similar for the other interactions, there's a gluon field for the strong interaction (Quantum Chromodynamics), and for the electroweak interaction there's kind of a combination of the photon field and the weak-interaction-bosons.