If the entire car stopped while actively driving, it's not coils or your starter. All 4 ignition coils don't just die at the same time, youd have one go out which would result in a misfire, not complete shutdown. And your starter has zero impact on the engine while engine is already running.
Being that it's a Theta II engine with 75k miles that no longer turns over, it's likely had a catastrophic bearing failure and has completely locked up. They were a flawed engine design with poor machining and a very high percentage of them die at that mileage, so much so that Kia recalled millions and has been sued over them hundreds of times.
Don't waste your money parts cannoning that shit, especially when you aren't experienced. Take it to a real mechanic for a quick inspection, it could potentially be an electrical issue, but there's a high chance your car is basically totalled unless a Kia dealer is willing to replace the engine under warranty.