Well, first you would need to see if it's physically possible to connect the N8 camera to the system bus of N9. If it uses the same serial connection with same pinout then the first part's done, otherwice you need to build an adapter board between the equipment.

Of course. But that's just SW, it does not take up any extra space so assuming you have the exact specifications for both camera's HW interface then rewriting the drivers is trivial