You can’t afford not converting from h264 to ProRes. FCP doesn’t edit h264 natively. 30fps to 25 fps is going to be a problem, but the immediate problem is all your footage must be converted to ProRes 422 and the sound must be converted to 48khz.
If you choose to ignore this advice, which has been repeated here endlessly since the 5Dmk2 hit the streets, you will not be able to play the footage smoothly whilst editing. Search this forum for the best advice on how to go about converting your footage. The latest advice is to use the Log & Transfer plugin from Canon.