Home world choices and Finnish FFXIV communities

As a WoW player I've learned the impact your choice of server can have on your experience.

To what extent are the worlds separated from each other in FFXIV? For example in WoW you can have characters from different realms play together for some types of content but no cross-realm guilds or high-end raids. The XP bonus for starting on a new world is tempting and transfers don't seem to be nearly as expensive in FFXIV, but do you actually encounter players/communities from other worlds?

Also, is there are any particular world (or data center) with a concentration of Finnish players?

You can travel to other worlds on the same data center, party with and run instanced duties together with players from other worlds on the same data center, and have linkshells (private chat channels) with players from other worlds on the same data center, but your Free Company (guild) is limited to only players with the same home world as your own.

There's no in-game communication with players whose home world is on a different data center.


EDIT: I forgot housing. You can only buy a house on your home world. So Free Companies and housing are server specific and pretty much everything else is data center specific.