First they say the bullet made a curve, which implies that the marksman missed the aim and Magneto fixed its path into the president. Then he explains that he was trying to save him but they stopped him, probably just on the time when he was moving the bullet and it was directly into the president.

But, first, if the marksman missed it, why didn't he just le the bullet follow its wrong path?

And 2nd, if for any reason he wanted the mess with the bullet to avoid the killing, why didn't he just make it stop and fall on the ground?

And how did he originally flee from prison? Is there any mention on comics that he did that, got arrested and fled? If it wasn't for Wolverine to change the events, how would he get out of there?