Wow. So are you assuming every player that purchases the game would have a similarly large starting base?
Once you get your hands on Outerra you'll know why.
If we only count one quarter of total land area (148,940,000 km²) to be habitable, it will be 37,235,000 km². How many players could be there? Even if the whole WoW nation came with their 12 million players, each one could get 3.1 square kilometers (~1.2 square mile). Of course, in game there's more land
habitable than in RL, and most of the players are socializers who will join an alliance and share the land.
With 10,000 players it would mean 3723 km² of
arable land or 14,894 km² of any land for everyone.
As for the customization - mostly everything should be customizable, the design of base and infrastructure is player's to decide. Until there's a building generator that can generate say a storehouse, hangars, and any other buildings from a template with player defining what area it will occupy and changing the layout, there will be probably static models initially.