On the first part, not really? I see no reason why his characterization would somehow change if you replaced Stark with Pym in his creation. I'm pretty sure they still would have had Ultron act just the same way that he did (and by pretty sure I mean 100%). Agreed, the Stark origin didn't make Ultron automatically better, but I never argued that. I just said it makes a lot more sense than Pym creating him. And it does.