RE: Control horn and Plate alignment.
I use small T-pins for this purpose. Push the T-pins through the control surface and eyeball them to make sure the pins are parallel to each other. Slap the back plate of the control horn on and double check to see if all the pins will go through the holes in the back plate. If not, remove the bad pin and try again. Once all the pins line up, remove them and drill the control surface with a 1/16" drill bit first, then go to the next larger size if necessary.