Until starbase introduces zoomable camera objects, which I've heard they're not intending to do, it's going to be impractical to do super long distance sniping of any sort, station or otherwise. If the slightest nudge of your camera veers your aim off a dozen meters or more, you cannot target station defenses. They can't target you either, but they don't need to until their immunity window is down in the first place. This being said, I think for the most part station defenses probably aren't going to be much of a thing. They might have some turrets just to keep people from getting too close and doing targeted attacks etc, but since targeting AI is not really supposed to be a thing in the game and stations can't move, it seems much more likely that station defenses will mostly be in the form of heavy armor to deflect and withstand attacks, while active defense comes in the form of mobile ships that can target enemies better. Since it would be mostly a waste of player's time trying to shoot at something so far away they can't really see it and have to just fire at whatever is making a light show in the distance. There will probably be much more of a call for anti-boarding security personnel, but in all likelihood that will mostly result from respawning players who died during the firefight outside in the first place.
It seems pretty likely that the ability to respawn at a station will be one of the biggest defensive advantages in the first place since it's looking like on-ship respawn will be either extremely limited or nonexistent, at least at launch. Stations also will be able to spawn new ships if they have resources. Attackers will have to respawn at whatever is their closest station, and will be much more limited in keeping up the numbers of ships in a station battle (they can use carriers to bring extra fighters but that doesn't help with the large ships that will be the heart of the fleet, and those fighters will only help if your pilots avoid dying when their fighters do). The way I see it, station battles will be very likely to become massive sieges where you attempt to prevent your opponent from bringing in new resources, while you need to build your own starbase as close to theirs as possible and slowly creep in on their territory to even reach the point of having a siege.