The answer to your last question, Le Messor, has to do with what happened to his father (earthly) and the fact that he did nothing about it.

I thought the movie was good. It explained how one man (alien) could come to care so much about the planet he called home, in away that no other Superman movie had yet to do.

I will say this, though; the death and destruction was on a HUGE scale, on par with the Avengers movie. I have a real problem with skyscrapers being destroyed and believing that there was nobody in them.