I said yes to both questions. Like others, Clark did seem to start off unpolished, but grew into his character. Part of that, I think, stems from actually getting the girl. He was always pretty worried about ever attracting Lois' eye in the first couple of seasons, but once they were together, he exuded far more confidence.
As for the geeky Clark Kent in the Reeve movies, that was the way Clark was back then. When DC Comics rewrote their universes, and all their superheroes, they changed his background as well as those around him. Back then, Superman was the real person. He made his Clark geeky to hide his identity. So when Lois admitted she loved Superman in the second movie, Clark was happy about it, not caring that Lois didn't care for his disguise. L&C Clark would have flipped and run away, thinking Lois only loved the cape. The new Clark, after the DC rewrite, was far improved. He also had a dad who survived past his teen years, too.
They also weakened his powers, too. The old Superman could push the earth out of orbit, for instance. The new Superman couldn't come close to that.
Lex also changed, I think for the better. Before, he was a mad scientist. He became a businessman after the remake, a far more interesting character that leads to far more interesting plotlines. A mad scientist as chief antagonist would have made L&C far too cartoon-like, just like fourth season ended up doing, which IMO, killed the series fast with really stupid villains like Fathead.
