Thanks, its all updated and I hope I caught all the typos.
I'd like to point out that this method of determining AOB angle is not limited to Parallel attacks.
Parallel course and matching speed to targets are preferred but not necessary. The advantage of a parallel attack at matched speed is that the AOB angle remains fairly constant allowing you more time to enter it into the TDC. So its a good way to start learning manual firing.
If need be, I may expand this tutorial to demonstrate the same methods used above but at a different angle of approach.