Question on Cut Throat Invading

I'm from NZ and will be playing on the US server during the second cut throat event this weekend. If someone else invades my instance will they then switch over to the US server?

Why should CT be different to regular leagues? You can easily party up with players on other gateways without any change on them...

I would assume that whichever server the instance is created at is where it stays.

If that is true, in the future it will be important to indicate where in the world each instance is located so players can avoid, say, invading an instance that raises their ping from 50 to 500.

There is an alternative that could exist... their gateway servers could be abstracting a level of play from a central server, using prediction, and pushing the data to gateway servers. So effectively everyone is playing locally, but the central processor is in one particular location. I would think such a system is too complicated to make reliable... so I doubt this is the way it's done.