I definitely recommend GWX for more realism and texture. About Manual Targeting, At least learn how to do it even you don't want to use it, since that’s where all the fun is .
Here some helpful documents available on Subsim :
How to Intercept a ship and The Hunt : http://www.subsim.com/radioroom/down...o=file&id=1081
or
http://www.subsim.com/radioroom/showthread.php?t=88961
How to Calculate the AoB :http://www.subsim.com/radioroom/down...o=file&id=3467