Deep frying

it depends, i don't like OO for frying because it has a low smoke point and can scorch out and give a bitter taste. it's also more expensive. for general frying i prefer canola or veg

dredge/eggwash is really a personal preference and subject to style. depending on what i'm cooking i might do flour/egg/flour or flour/egg/seasoned bread crumbs and then deep fry or shallow fry at a lower temp with butter added.

no matter how you roll, oil temp is critical. if the oil is too cold you'll just get a gloppy mess and the breading will fall off, or it'll just be super saturated and not crisp up and taste more like oil than anything else.

i love my air fryer, but it don't do chicken fried steak like the cast iron does.

ETA: you could also go full villain (and pay for your cardiologists 2nd house) and just fry in lard.