No, like with a cast iron skillet, the hard, black, very-attached, coating is the burnt oil. Cast iron and carbon steel are normally shiny metal, not dull black, without this layer.
The oil fills the pores of the metal and polymerizes. Subsequent layers cross-link with each other to develop the non-stick coating. It doesn't really 'come off' although I'm sure small amounts will occasionally. It doesn't contribute to flavor and it's not exactly toxic. Same deal as cast iron, details here. [1]
Most oils polymerize at high temperatures. Getting the temperature juuuust right is pretty tricky in a home setting. Much easier is to just burn the shit out of the oil and wipe away the burnt oil, leaving any oil that happened to polymerize behind.
This is in fact how they used to make linseed based paints. They'd boil the oil, setting the stage for it to polymerize, and add pigments. The oil would slowly polymerize after being applied, locking the pigment into place. These days I think they mostly use chemical accelerants instead, Which makes the curing times much more tolerable.
only if you don't clean out your pan. Any youtube video on seasoning it will explain it quite well. Seasoning isn't "burnt oil" by any stretch or chemistry.
