Good post.
However, my main problem still stands. There is no incite to what it takes to bend lava. Bolin simply gives it a shot and does it, and we're never given any explanation to how Ghazan makes and bends lava. All the other advanced bending techniques are given some sort of explanation:
Lightning: Explained by Iroh in Bitter Work.
Metal: Shown and explained by Toph and Guru Pahtik in The Guru.
Blood: Explained by Hama in The Puppetmaster.
Combustion: Never directly explained, but given how Combustion Man and P'Li both had the chi tattoo, that can be inferred as the requirement.
Energy: Explained by the Lion Turtle in Avatar Aang.
Flying: Explained by Zaheer in Enter the Void.
Even Jinora's astral projection was given some sort of explanation. It was a bit half-hearted in my opinion, but that's another story. We even got explanations for how some normal types of bending worked. According Toph in Bitter Work, earth bending requires you to be firmly rooted both physically and mentally. In the Sun Warriors, firebending, though twisted by the Fire Nation to be fueled by rage, works by understanding that it's life and energy in the body like a sun inside you, not just destruction. It also comes from the breath, so proper breathing techniques are necessary. A nod to dragons breathing fire I suppose. And of course, we received plenty of explanations for how airbending works by Tenzin training Korra. Be the leaf and all.
But lava bending...nothing.
Before this season, I always assumed that lava bending would require a lot more ebb and flow techniques, like a waterbender. Which would explain why typical earth benders wouldn't be able to do it, and why Avatars are the only ones we've seen bending lava before since they know how to waterbend and apply the style to lava. But I sincerely doubt Bolin decided to bust out some waterbending style at the last moment. And we weren't given any clue about Ghazan studying waterbending moves either, so my theory is pretty much dead. So how does it work? Is it something that any earthbender could get the hang of easily, just like how any waterbender can bend ice easily? Very doubtful, Mako and Suyin's reactions made it seem like it was a rare skill.
I don't know, I guess it's not that big of a deal, but the main thing that bothers me is that I have no idea if Bolin can do it because of skill and technique or if he's just unique. Does he know what he's actually know what he's doing when he lava bends and the difference what that requires compared to normal earthbending? Or is he just throw his arms around, straining and grunting, and it just happens to work? Some insight would be nice.
Actually, I think the very first time you see Ghazan bend lava we see him twisting some rocks until they eventually become lava. That's definitely not much to go on, and Bolin never sees this, but it at least suggests to the audience he's simply taking Earth and superheating it, likely through friction.