Lodge specifically instructs to heat their cast iron on high before adding food/oil in their cookbook.
That’s only for a short time, though, and once you drop the food in, the temperature drops.
And I would never heat a cast iron on high on a coil electric. At least, I wouldn’t do it again. I know mine got over 800 degrees on medium high and total destroyed the seasoning. Any oil thrown in the pan would have instantly ignited. My current stove is an induction and I don’t know how hot it could get a pan.
That’s correct. You heat it on high until you add the oil or food.
Bobby Flay uses his cast iron on open flames.
Don’t you season after each use? The Lodge Cast Iron Cookbook recommends you wipe with oil after each use. I use melted shortening.