replace logic board and video card with updated

I am weighing the options on repairing my A1312 3.06 core 2 duo logic board, or if it is compatible installing a Core i5 or i7 board from the 1312 model line. Will this quad core board drop in place of my core 2 duo board?

I was also thinking about upgrading the graphics card while I had it torn down to that point, would the graphics card from quad core board also be a drop in?

If I decide not to upgrade the graphics, will my current graphics board still be compatible with the quad core board?

Thanks,

George Harrison III