For the smart link question, I think mirikon and Narrotor have the giest of it.
To me a smart link is actually 3 pieces of ware coming together.
1: the link in the gun is a dedicated piece of hard/soft ware calibrated to the weapon to provide the absolute best knowledge on the trajectories and ballistics of the weapon.
2: the meat link installed in the person that takes the info from the gun translates it to meaningful input and sends that to ....
3: the visual receptors of the shootist, displaying the projected point of impact on the target inrelation to the position of the gun.
As how a simrig, etc could replace cyber eyes/ears.... Not too sure what you mean here. An implanted commlink would allow you to bypass the subvocialization for sure (and you could probably do a 'sore throat' through thought as well!) Also the input from your implanted comm would allow you to not need cyber eyes/ears to see text messages or hear calls.
But you would still need SOME sort of receptors for any of the nifty things eyes/ears can do.. (flare compensation, thermographic, low light, magnification, etc for eyes. Low range, high range, spatial, dampening,etc for ears)
However, you could just go with headphones and shades with those features built in and the DNI'd to your comm to broadcast.