For the smartgun thing, I think the way that should go for gameplay purposes is that the player needs to hold the reticle on a target until the gun "locks on". That should take a few seconds, maybe even 3 or 4 degrees of "lock", each of which gives a better percentage to track and hit the target. I supposed it could be augmented by some sort of "skill / perk" like Steady Aim that decreases the amount of time to lock on.
I don't think it should be "hold down trigger until ammo is depleted". There should be some semblance of gameplay challenge to using them.
Almost exactly like what I suggested earlier (a good number of times -- also found from the link in my sig). With the exception that I'd give the responsibility of locking and holding on to it to the player (for as long as he wishes, but only as long as the governing stat allows), and the hit-chance being a living metric based on the situation (movement, distance, etc) and how good the character is with the skill.
For FPS gameplay smartguns are a bit difficult to model, as according to CP2020 they're a "to hit" modifier and that's (almost) entirely up to the player in an FPS. Maybe (as much as I hate to suggest it) a minor, say 5-10% damage modifier to represent more accurate shot placement? So smartguns are beneficial, but not overwhelmingly so.I think for smartguns, when you cursor over a target, you get a blip on it and an audio tone as long as you have the "aim" button up. Let the button go and the weapon fires. Kind of like how they are supposed to work in the PnP.
For added systems depth, how accurate the round is could depend on your weapon skill. Or where the target pip lands. Better skill = pip goes from torso to head to face to eyes, etc. Bypass armour, etc.
Autofire is tough to do with smart weapons, because you have to -think- fire for each shot. Instead, have it an AoE - a big hit zone or multiple hit zones on multiple targets.
For RPG gameplay however a short time (say a second) to lock onto the target works pretty well. Make the targeting reticle large enough you don't need pin-point aim but not nearly as large as we saw in the press demo. You can then have the pretty much autohit. I'm most definitely not in favor of the giant target area and hitting everything in it we've seen. I'm not sure the audio tone would work as it would be a "reaction time" issue, how long does the tone last? Do you have time to react to it? I'm also not sure giving smartguns pin-point accuracy (allowing you to bypass armor with face shots) is a good idea. Yeah they can lock onto the body, but onto the the left eyeball? Just use the standard random hit location charts in CP2020 for where each smartgun shot hits.