I think it would better serve the film if you tried to keep it faithful to the original font personally.
Super Crystal 2 with Intro
I think it would be better if the editing was as quick. As Supes throws the missile into space I think it would be better if we saw a little of supermans reaction as he threw it and of the missile being thrown. Basically, use as many frames as you can.
Then when the missile is thrown into space I would use footage from a movie where we see a nuclear missile going through space (Superman 4 has the perfect shot, but it would involve pasting out Supermans flying cape)
Then by lowering the sound, have it running out of power and then the explosion.
Then The Phantom Zone exploding.
Really like how you did that by the way, along with Supes looking to the other missile and diverting his attention away from Zod and co. Really adds layers to when you watch STM!
For the intro, you could fade in to the sound of men talking...
Its Lex speaking to Superman about his plans, saying he gets around a lot. Then have Lex saying about a nuclear missile at this exact location etc. then have him pounding it with his Stick.
Then have the footage of the first missile being fired etc.
I would also use the music from Superman The Movie because it sounds better than Ken Thornes (Williams had a bigger orchestra)