Thank you for the replies Jason!
1) So to confirm, you tapped into the interior receptacle and you extended the 12/2 to provide the power feed into the exterior GFCI, correct?
2) If correct, then you do not have any other downstream receptacles connected to the LOAD side GFCI screw terminals, only the LINE side, correct?
3) Did you splice the bare copper from the new 12/2 onto the bare coppers at the inside receptacle box?
4) I assume that both the interior and exterior boxes are both metal and not PVC plastic?
5) There is no need to tape the ground wire. However, I always wrap a few pieces of electrical tape around the entire body of the GFCI to make sure the hot brass and/or silver neutral screws do not come in contact with any ground wires or metal sides of the box.
6) When you plug-in the GFCI cube tester without intentionally using the trip button on the tester, what do the colors of the tester indicate? An open ground or something else?