^To the first one:
Why does this bother people? Droids are likely mass produced, like cars are in our galaxy, so it is no less plausible for Owen and Beru to not recognize C-3PO (who looks different in Episode IV than in Episode II anyway) and R2-D2 (who is only one of who-knows-how-many astromech droids, since we see at least a dozen in the prequels) than it is for a person to recognize a re-painted truck they once owned, and a car that belonged to someone who visited the neighbours.