Regarding the AI's warlike tendencies...

[Blake]

May sound dumb, but the best way is to stay a bit weak. Not too weak, about 3rd on the power chart is right. The best way to do this is to not pop-boom at all and avoid having much of a military while not being greedy for SP's - settle for the Empath guild and 1 or two of the early ones. Run Neutral SE's and be accommodating to their demands while demanding they make friends with each other. Find a scapegoat, the AI's must be at war with someone so do a Bush and invent world enemy #1 - this faction should be isolated so they won't actually get attacked and will never sue for peace, a naturally obnoxious faction like Miriam or Swen makes a good choice. This way you can easily mantain pacts with all factions bar the scapegoat, forming a giant powerbloc of pacts and treaties - the commerce income can be amazing and makes up somewhat for the lack of SE - with all factions recieving loads of commerce and not focusing on war, the AI's becomes pretty good at research.

When it comes time to win, pop-boom and win planetary leader. You could probably transcend pretty fast too.

edit: A nice manipulative trick to get a faction to pact with you is to make them be at war with everyone, while not soiling your rep too much. Pacts and treaties count towards power, so once they are isolated their power falls, and suddenly they are desperate to have a pactmate - any port in a storm.
You can also temporarly treaty with the scapegoat, in order to get the faction you want a pact with to do the "renounce your friendship with and come pact with me" thing.

[Velociryx]

Just play as if the AI wasn't even there. With the exception of getting found and tech-extorted before I'm done building early infrastructure, that's my usual plan....if I have decent military techs and have largely secured my starting continent, I'll flatly refuse every extortion demand and never really even give them a thought until I am utterly and completely satisfied with my empire. Then it's time to roll out a few hundred cleansomethingorothers and stomp the folks who have been "at war" with me off and on for the past 75 years...

-=Vel=-

[Commy]

Let's just put it this way: the AI is going to lose anyway, so at least make their lost a memorable one.