Weapons should have engagement thresholds… i.e. they don’t attack targets of particular size. This is to prevent your heavy slow-tracking weapons wasting themselves on fighters or frigates that they cannot hit anyway. Likewise prevents fighter weapons that can’t scratch a cruiser from bothering to engage them.
This should be a weapon limitation, so your cruiser anti-fighter weapons will still work.
Also needed: Far larger maps!
HELL YES 
You can set the map sizes arbitrarily high as far as I can tell.
doesn’t change the fact that EVEN BIGGER ones will be able to house insanely large fleets. make it so! 
If there weren’t a 256k limit to jpg sizes, I could post some of the 4096x4096 backgrounds I’ve created.
GIMP is a wonderful tool…
uh, 4096x4096 is the EXACT size of the large backrounds (already in the game) 
I made an 8192x8192 map, and used one of the stock backgrounds, and I guess it just scaled it up.
oh… THAT’s the size we need, xD
The dimensions of the backgrounds I have in the background directory (C:\Program Files (x86)\Gratuitous Space Battles\data\bitmaps\backdrops under Vista x64) are 2048x2048. Where did you get the larger ones?
The default gunner AI is supposed to give weight to what the gun being used could actually hit. Of course, the weight is an unpublished detail, so experimentation is needed to determine how not to screw it up by, say, over-priorizing fighters such that the cruiser’s plasma gunner tries to hit fighters that he just won’t hit.