Am I correct in thinking radio waves are transmitted by virtual photons with polarizable properties, which can be affected by other fields?
Nope. Like I said earlier, virtual photons are responsible for exchanging energy and momentum between two charged particles. Photons (whether virtual or not) are not directly affected by fields.
If you have some system of charged particles and then impose another electric field on the system by adding another charged particle, then the charged particles will interact with the new one as well as each other. Consequently, the number of virtual photons flying around to exchange energy and momentum among the charged particles is higher.
Radio waves are EM radiation. EM radiation can either be described using waves (which sometimes works but sometimes does not), particles (i.e. real photons, which also only sometimes works) or quantum particles (which always works, but often the mathematics is not conveniently tractable for macroscopic bodies).
And Maxwells equations describe virtual photons not real photons? If so, do you have a good reference.
Maxwell's equations describe electromagnetism. If you want a framework to adequately describe virtual particles, you probably need to look at Quantum Electrodynamics (QED) and/or gauge theory. If you want a framework to adequately describe real photons, look at particle physics, quantum mechanics (QM) and QED. I studied particle physics and QM at University, so I can help with those to a limited extent, but I know absolutely nothing about QED or gauge theory..
Furthermore what are magnetic field lines made up of? Are they dressed electrons? virtual particles or what? They bend, and travel through solid material, that would absorb or reflect photons.
Field lines, for all fields, are an abstract concept used to characterise fields and, consequently, how objects with certain properties are able to seemingly interact without touching each other. They're not made up of anything.
There's a philosophical debate to be had about whether "fields" really exist. I'm sure there are people who really believe that fields are out there in the material Universe and can be considered as "stuff", but, if so, they are unique and not composed from other things... certainly not virtual particles.