(This can either be in terms of FreeSpace ships, or in general, so I wasn't sure whether to put this in General FreeSpace or General Discussion or Fan Fiction ... etc.)
What would a realistic ship be like?
I designed a ship recently that was meant to be 'realistic'... it was armed with 4 forward-facing turbo-powered energy weapons of some sort, 6 railgun turrets (two barrels each, the barrels being approximately 1 meter wide), and 4 arrays of zero-profile missile launchers. Its engines were in the rear, but were spaced as far as possible to make it as maneuverable as possible... putting all of the engines near the center of the rear section does not make it faster, and if anything reduces the ability to accelerate angularly.
What would a realistic set of weapons for space combat be like?
I think for short to medium range, railguns would be ideal. They fire projectiles that are very hard to intercept or avoid, and release an explosive amount of energy on impact (pretty much as much energy as you put in when firing).
For longer range, missile are ideal. They can track a target, and don't require much energy to fire, so you don't need huge capacitors or anything like you might for the railguns.
For strategic weaponry, I think the best you can do is a nuclear railgun round. Fire it with a railgun so it can't be easily detected/intercepted, and give it a huge payload to send the target and everything nearby to kingdom come.
Nukes also emit tons of x-rays, which could in theory shatter a ship's hull.
Lastly, lasers: they're invisible, as close to instantaneous as you can get without bending space-time (which we don't know how to do), and release about as much energy as you put in.
Now you give some ideas...
Compare to FreeSpace, or not, as you please.
Keep it real.