Ah, thank you both. To see if I could get the "Kill 1000 frigates" achievement, I edited the cost and construction speed of light frigates to almost nothing/instantaneous (respectively) and picked 4 aggressive AIs on the hard setting. Yes, instead of, say, 5 light frigates they had more like 15-20, but they still built the usual variety of ships.
Not to mention the part where, yes, they did assemble a MASSIVE combined fleet one planet away from my homeworld, but all they did was sit there! I was thinking "ok guys, between the four of you, you'd be able to pretty much instantly destroy my planet. So WHY are you waiting?!

" /sigh
Anyways, after my original post I found a similar one in the forums explaining that AI behavior was stored in the *.exe, and I think I'd rather try to change out my car's fan belts while the engine's running than to mess with that

And also, I did find the part in gameplay.constants that Annatar11 referenced, but it'd be nice if we had more access to some of the finer points. I'm particularly interested in where it says: "if enemyFleetSize > x then retreat()" I'd really like to change "x"

I'm tired of bringing my large armada to fight with their armada then their armada goes "We're just as big as you, but for some reason we're going to retreat" (???)
Oh well. Maybe in future patches? Of course I can understand Ironclad's desire to maybe not share the entire inner workings with the general public ^^