Krillin, no doubt. He's the most powerful human on Earth (I think), but look at the way everyone treats him. If Krillin didn't live close to all of the Saiya-jins, he would probably be treated like Mr. Satan.
Why does Turles (from the 3rd movie) look just like Goku? There doesn't seem to be any logic behind it, it has virtually no relevance in the movie, and they aren't even related (other than them both being Saiya-jin). Quite frankly, I think this is a question with no answer.
I think that the movie was made around the time that Goku was fighting Ginyu, and he went all red like in the movie, which was right after Vegeta determined Goku was a Super Saiya-jin, so...
that's why it's called "Super Saiya-jin Goku".