I was just wondering if changing SD Card makes any difference in the footage also all the files from the original SD Card won't be on there do you have to transfer them onto your new one?

The one I have bought is a 64GB sandisk ultra SDXC 48Mb/s class 10 is this good enough for my P3A?

The one you have bought is just able to work with your P3 Advanced. You do not have to keep any of the files from the original card. Just put the new card in the aircraft and format it using the Go App and it will be ready to go.