But makes you think why these super advanced aliens who once had a galactic empire didn't do more to save themselves.
Because they're rigid and unwilling to admit their mistakes and don't believe Jor-El's claims that the planet core is going to implode. Zod was the only one who believed Jor-El about the planet's fate, which is why he tried to overthrow the Council.
Apparently the Kryptonians just can't survive outside of Krypton but Kal didn't have any problems doing so.
Yes they can. They had colonies all over the nearby galaxies. The colonies eventually died out for various reasons (cut off from Krypton when it banned spaceflight, attacked by other aliens, starvation, disease, what have you).
Kal-El experienced the same problems adjusting to Earth's atmosphere and other environmental conditions that the other Kryptonians did, it just happened when he was very young. Martha said he used to have terrible breathing problems as a baby, and then, as you mentioned, he had the same sudden, overwhelming appearance of his x-ray vision, super hearing, telepathy, and so forth.
If Zod had simply been patient, he and his people could have acclimated to Earth's environmental conditions as well and lived there in peace eventually. He was just too arrogant and indoctrinated/programmed for war to wait for that to happen.
And making out just after possibly thousands of people were killed by the tide of destruction caused by Superman and the Kryptonians? That was in bad taste and terrible timing. They were practically standing over the dead whilst snogging. Jeez.
They were relieved to be alive and to see that the other was alive to. It's a perfectly natural response. Even with all the deaths and destruction in war, the first thing people do when they see their loved ones is to hug them and kiss them.
My problems for the movie where I didn't really feel it was a Superman movie. You could of slapped any superhero into that role and it would of worked.
Any superhero that's a godlike alien from a dead planet that's adopted by farmers and raised as a human who then has to protect Earth from his fellow aliens, sure. There's a few similar ones, but it's hardly just like "any superhero." Captain America couldn't have been slapped into that role and have it work.