First let me say that SR is not without some flaws, but still it is better than Superman 2, Superman 3, Superman 4. The character of superman is same as in STM and S M 2, it just progresses from there. Superman leaves for New Krypton without saying goodbye to Lois and she tells Clark Kent that he should have said that later on in the movie when Superman decides to lift New Krypton in the space, he says "Goodbye Lois" knowing that he might not survive lifting a Kryptonite studded continent, that is character progression right there. Lex knows that the first threat that he will have to face is Superman, and he is waiting for him and he is prepared (although that involves Kryptonite, again.) the low intensity Kryptonite radiation that Superman cannot detect while flying at some height, starts to affect him as he lands on NK because it poisons him not just depowers him. As for dealing with army he was prepared with the knowledge of making weapons from crystals as he say something to that effect in the movie, but it is not shown.