On the other hand the waist mount seemed only stablizing the smart guns...
however: long live ms. vasquez!

That's because that's what that harness
actually was, a Steadicam harness modified to hold the prop smart gun instead of a big movie camera. The actors had to move it themselves because with a budget of $18m IIRC there's no way they could've made a motorized one!
The eye monocles certainly implied targeting, and if not why else would they call it a "smart gun"? It was obviously a reference to the then-new-to-the-public "smart bombs" that hadn't been used in Iraq yet but were already common knowledge to those who read about it. A gun you aim yourself is a "dumb gun".

The other thing is while the smart gun aims itself, it doesn't aim very fast at all. The slower movement of the soldier you can compensate for, but if your target is zigzagging faster than the gun can track, you're SOL. Most of the AvP games let you turn off the auto-targeting and frankly I found it to be MORE useful that way. I'd say the smart gun was more like a SAW with auto aim as far as its accuracy goes.
The Jedi Master