(...) 1) I can't help but think that the computer is cheating some how. (even when the game promices that it is not.)
2) Also, another thing I HATE about these games is that no matter what I do, the computer player always wants to go to war with me even though i'm not even in the lead, and never antaganized them at all.
3) the 2nd thing I want to se in Gal Civ 3 is the abillity to turn off the computers abillity to declare war. that way, they can only go to war when I feel like doing so.
1) The computer is only "really" cheating in one respect:
It knows where all the habitable planets and starbaseresources are. Getting a properly working exploration modus going for an AI that actually resembles what an experienced human would do is very very difficult. This is compensated by the fact that the AI will build scouts, and too many of them too generally (costing production and upkeep), while the human player will explore with his/her colony ships.
On levels above "Tough" it will furthermore start receiving boosts to its production, research, economy etc., but it doesn't create production out of thin air, it still needs to build the buildings, increase the population etc, they are just more effective. This is not really cheating as the computer doesn't do things that are "impossible", it just becomes more effective to givet he experienced player a (much) harder time.
2) The problem is exactly that you AREN'T in the lead militarily. The AI judge diplomatic relations by a variety of factors, an important one is their assessment of whether or not they can take you in a war. The weaker you are militarily, the more likely the AI will try to pry planets from your cold, dead hands to bolster its own empire. The AI is trying to win just as much as you are, and picking on weak civilizations (such as a demilitarised player) can be an important part of that. Furthermore, just your existence can be "antogonising" to the AI, through mismatched ethical alingments, close borders or a weak diplomatic skill on your part, it can grow to hate you, even if you've done nothing actively to upset it.
3) I'm all for more options, but making it impossible for the AI to declare war, really does take the I out of AI. What's the point of having opponents if you're the one that decides you're ready to crush the AI at last? You can, however, mess with the likelyhood that the AI will declare war, and unlike stated above, you do not have to create whole new custom races. You can very easely customize the standard AI races, by editing their files in game. Simply start a new game, select the opponents you want, and select each of when, and then choose "edit". One of the things it will let you change, is the AI aggressiveness. This will have a huge impact on their thirst for blood.
Making it easier to see what the AI is doing if you so please, can be interesting, especially for the modding community. But I don't know anything about GalCiv2 cheats, so perhaps there is already an easy way to do this without needing to explore the enemy territory and spying (or switching seats).