I am not an expert on this, but here are my thoughts.
1. Space fighters are quite unrealistic. In aquatic navies, they are useful, as aircraft travel through the air while ships travel through the water, so they can go faster, maneuver around their targets, attack over the horizon, etc. However, both large and small craft travel through the same medium in space. There is no reason why fighters would be any faster than capital warships, and while they might be more maneuverable and have faster acceleration, they will never be fast enough to dodge lasers at close range. In space, there is no horizon, so enemies can be spotted at immense ranges (Voyager probe can still be detected from Earth, and any interstellar spaceship's engines will use enough energy to power a modern nation for days at the very least), so fighters cannot hide. If you want to attack enemies at a distance, you would use missiles, as a fighter takes four times as much delta-V as a missile to hit its target (it needs to accelerate to the target, decelerate, accelerate back, and then decelerate, while a missile just needs to accelerate to the target), so carrying missiles would be much more efficient than carrying fighters. The weapons carried by a fighter would also likely be pointless, as capital warships would carry much larger weapons. The fighter's railguns/lasers/etc would be much weaker than those of the capital warship and would barely scratch its paint, while the capital warship could detect the fighter from huge distances and melt them with undodgable lasers before the fighters entered the range of their weapons. The capital warship also has a higher volume to surface area ratio, and can thus have much thicker armor with the same ratio of armor mass to other mass or the same armor with much more mass available for engines, sensors, weapons, etc.
2. You probably don't need to aim in many different directions in space combat. Space combat probably does not consist of dogfights or slugging matches. 898
Instead, spacecraft spend hours, days, or weeks maneuvering to get into position, then fly past each other at incredible speeds, firing on each other for a few seconds during the intercept. As such, you would not need to have weapons in all directions, and doing so would be very inefficient. Military spaceships would probably consist of two cones attached at the base. The front cone would be heavily armored and would feature all or nearly all of the craft's weapons, and would be pointed directly at the enemy to maximize the number of guns capable of firing on them and the sloping of the armor (remember that a spacecraft does not need to point in the direction it travels in). The rear cone would have the engines as well as the delicate radiators, which are hidden behind the front cone (space is cold, but it has few particles, so heat disperses slowly. Any spacecraft needs radiators capable of emitting heat as IR radiation, as without them, it will cook with the heat of its own electronics (though some spacecraft with less waste heat might get along with radiating heat from their hull)).
Spaceships travel at incredible speeds, and humans just do not have the reflexes to aim at targets moving at dozens or hundreds of meters per second that are hundreds of kilometers away. However, you could still justify human gunners. Maybe all humans have a tiny bit of innate precognitive ability, which gives them a small advantage over AIs. Your ships would feature some direct brain-computer interface that connects gunners directly to the ship's computers, giving them the processing power needed to actually hit enemy ships by melding their minds with that of the ship. The trajectories of their own ship, the enemy ship, and the projectiles would be calculated by the computer, the humans would use their special spark, whatever that is, to make necessary adjustments, and would then would aim the guns with thought commands (no human can move physical controls with the speed and precision needed to hit moving spacecraft). You would use humans instead of brains in jars to save mass, as the gunners can perform repairs and maintenance outside of combat (remember, direct combat only lasts a few seconds at a time). However, the gunners would probably not sit by the guns in turrets in actual combat. The turrets would be automated, and the gunners, along with all the crew, would sit in an armored citadel located at the rear of the ship located behind the propellant tanks (which ought to make up a massive part of the ship in realistic sci-fi) , strapped into shock absorbing seats to survive the accelerations involved, and wearing vacuum suits to maximize chances of survival if decompression occurs and most of the ship's machinery, and operate the guns via multiple redundant wired and wireless connections. 898