Yep, after I get the achievement for a given victory type, I usually turn it off until only Domination is left.  There is can be no other ending to the story of my empire!

That said, I tend to be fairly uncompromising in diplomacy, so I leave Allied victory on: anyone willing to buddy up with me and stay by my side throughout is welcome to become a thrall race in my galaxy.

If all the planets are colonized, and you start conquering the galaxy, you will win an influence victory before the last opponent falls.

Not sure if this is still the case, but it used to be that you couldn't win the influence victory if you were at war. That way if you are actively conquering the galaxy you shouldn't be interrupted by the influence victory.

No idea. Diplo' was out of the blue, but in hindsight that should have been an obvious win con'. I kind of thought, with the United Planets, that I had to be elected ruler similar to MOO2, and couldn't just win an allied victory. Hell, I would think that all my allies would have to be allied to get such a win, but I know for a fact some of them hated each other.

That's why you RTFM.

Also, is the starbase spam real for everyone, or just me? I feel like you just get to a point where every planet needs three to four economic starbases, and you have to mine everything. I realize I could just build a fleet and kill people, but when no one's trying to fight you, you build econ', right?

i think brad said in one of the interviews during beta something to the effect of

starbase spam was a real annoyance in gcII and i think weve hit that nail right on the head

I still dont understand why that was a goal