Not exactly – the "Homer Simpson" yellow emoji came after the initial (Apple) emoji font, which just had all the humans looking white, with no other options.
This is untrue. Not that any of them look like Simpsons characters, but the only emoji option on iOS for like five years was the yellow-shaded cartoon face. It's still the default skin tone in most emoji sets.
This is false. The first emojis were Japanese in origin and were the first to use yellow faces. Apple copied the existing style from the Japanese illustrations.