I would actually change one thing in particular: Clark Kent with glasses( Metropolis Clark)would just appear in the last 10 mins of the movie.
SHOCKING, HUH? CONTINUE WITH ME ON THIS.
He would just be Superman all the time for most part of the film. A man in a colorful costume who wants to save the world and bring hope to people, And, also, find out his place in our planet and where he comes from. He won't even think about a secret identity at first. Why would he need one? He is powerful, sees everything, hears everything. Until some bad stuff happens through the course of the movie, particularly the end... wait and see! It is a much more realistic take, So, you'll follow the whole journey before it gets to the point we all love and care wich are the chemestry and fights between Lois & Clark. This time done with justice. No Smallville BS.
Because of that, my Superman would be characterized as a much more lovely, kind, less god like person in personality. No saviour as shown in SR BS!! He would be just a man with an ideal. In fact, he would work with Lois, who would be his PR person, to find out the truth about his origins, Brainiac and "dethrone" Luthor. In th end, when Lois thinks she got the news and story, BAM! Here comes Clark, out of nowheresville with an exclusive. The rivalry and the fun begins!
Superman Starts.
Bring on the sequel!