Rotation of attatchment points

[Fingolfin]

2 quick questions:

How do you decide which direction is which on attatchment points?
And how do i do to change it?

Second, how do i make it so that only a part of the model turns towards it's target; kind of like how the cannon towers and the turret of custom made tanks do?

 

[xXm0RpH3usXx]

1. well, the attachment point is equal to the x = 0, y = 0, z = 0 in the attachments scene

2. rig it to a bone and name it "turret_xyz"

both could have been searched well!