First... I'm one of the "I'm hope this isn't a pet job" types. Personally, I think Turrets should be simple.

1. Single Target Turret - Set to a single target and fires moderate damage every X seconds for X second duration.
2. Cone Targets Turret - Attacks in a cone doing low damage every X seconds for X duration to targets in range.
3. Force Field Generator - Reduces damage taken behind wall by 10% for X Seconds, Reflects 10% Damage back on target.

Something like that... I'm all for the RONCO brand accessories. You set them, and forget them.