I'll try to answer.
Quote:
Will tribe creation be in?
Who knows? On the official updates thread they say nothing about the new features, so let's act surprised when they release the patch.
Quote:
Will you need a minimum number of members to start an in-game tribe? If so, how many?
I remember something like minimum 10 members, but don't quote me on that.
Quote:
How will a tribe lay claim to a tribal zone?
The founder should have a command or item that allows him to deploy the tribe's totem. Once placed, the tribe land expands around it based on the number of tribe members and will vary when the tribe grows/shrinks.
Quote:
How will tribal zones be dished out? By region? By number of tiles?
Most probably it will be a circular area of influence around the central tribe totem.
Quote:
How will the tribal zone be marked?
No information about that, yet. The totem will be an actual in-game thing (item/feature) you can see, but the tribe borders may not be visible or be marked in some way...
Quote:
How will terraforming another tribes zone be controlled or prevented?
Generally, only entitled (enabled) tribe members will be able to terraform the own tribe's land. There is no way terraforming outside the tribe's influence area or even other tribe's lands may be terraformed.