[Bosje]

auto target is active as long as you have the 'manual targeting' turned off

if you see yellow triangles underneath ships as you watch them through the periscope, you know it works. what it does is calculate the torpedo track for you (the turn which the torpedo makes after being fired)
it's not a guarantee for hits though. there are plenty reasons for torpedoes to miss or malfunction (or even do a full circle to hit you in the behind)
war is hell

SD radar (air) is always active, you have no control
SJ radar (surface) can be controlled by you but it has to be available and installed on your boat. check the systems/weaponry screen to see if it's there.

and play around for a while, you'll come to grips easier