Check that new Relationships screen. Higher your relationship numbers (Envoys and research are great for that) sooner you win. Negative relationship pulls you down, though.

AFAIK, even with locked teams, the first one over the limit wins, and all others lose. Should be interesting, I think. The new speed option changes the rate you gain points.

It's fairly simple. The game sums each player's positive relations and negative relations across other players. If the total positive is higher than the total negative, you gain points at a rate proportional to the difference (so, if you're only at +1 total you'll earn points much slower than if you were at +10). The total number of points needed is 75 * number of players.

This mode is definitely geared towards FFA play, rather than locked team. And more towards SP at that.

Yep, this is basically what people asked for, a toggle for how many people can win an allied victory in FFA.

Well, until I actually sit down and play it so I can speak from experience, it sounds like this feature will be predominantly used for FFA.  Limited number of winners is definitely a good thing, and this diplomatic victory should be useful in that context.  In a locked team scenario, which will still be the vast majority of games played, it probably will be disabled.