Theoretically, they could. However, it's established that certain repairs to a robot's AI are effectively the same as creating a new robot. So it wouldn't bring Atom back, just bring into being a robot that looks like him, has his capabilities, and has all the baggage that those two things would bring.
So the way Tenma treated Atom after Tobio died? That's pretty much how the rest of the world would treat Atom's successor.
On Tenma's hair: I think it's accurate to the original, ie pretty goofy. Tezuka's character designs are such caricatures that there's only so much you can do with them before you lose the character design entirely.