Will my profile carry over?

You can link your new PS3 soldier to your existing Origin account that your Xbox soldier is on (they will show up as two seperate soliders, I have 2 PS3 (rank 75 and rank 8) and 1 Xbox soldier (rank 46) on my Origin account), however your PS3 soldier will start at rank 0 since stats between platforms do not carry over to other platforms.  Any DLC that you purcahsed on Xbox that you wish to use on PS3 will also have to be purcahsed again on the PSN store since DLC such as maps or Battlefield 3 Premium is also platform specific.