Well, they roll 4d6 (drop lowest) six times, and assign to taste. At least, that's RAW in the 3.5 PHB.
Not at all via class, and it talks about "elite" NPCs, too.
I believe it's 12.2 compared to 10.5.
True. By 5%. And in my book, 5% is not head and shoulders above average people, especially when they're outshined by most "average" people. Sure, you're 5% better at hunting than the average guy, but you're a lot worse than the average hunter (because he has ranks). Sure, you're 5% better than the average guy at crafting (not that this really helps you), but you're worse than the average craftsman (because he has ranks).
You're 5% better than the average guy at things, unless they're invested in them (like it's their profession). And then you're worse, unless you're invested (by 5% still). Again, not head and shoulders in my book. Just a little above average.
Assumed as a cut above? Yes. Head and shoulders? No. Because of class? Definitely not (in my book). Again, just my take on it, but I'm totally okay with your interpretation at your table. As always, play what you like
You do realize that if your characters highest ability score is 13... you can make an entirely new character right?
And even if you gte an 18 in one score... 10 in the rest, and 3 in another... you can still make an entirely new character.