Sorry in advance for the long messaging, hitting all of your unanswered questions in one go:
Merging accounts is not possible at this time.
It is unlikely we would offer it either as the function could be easily abused for various EULA breaking functions.
I'm not sure I 100% understand your question, but here are some facts around what you're talking about:
You should not be able to run two instances of the game at the same time
We do not offer account merging
If you would like to change your username you can do this in the Account Management section on the homepage.
This feature isn't really intended for those who are already in the server that related to their origin but more for those who may have moved or live between two places, such as our Aussie friends. They may have originally made their accounts on the EU server, but have decided to change over to the NA server since the event times work better.
Furthermore, we have no policy against making multiple accounts on the different servers. I myself have a account for each server.
Yes, clans are unique to each server so if you move you will leave your prior NA clan.
We are simply not offering it at this time.
Everyone who opts in to be moved, will be moved to their server of choice.
We do not offer a universal server as ping would impact players that are not close to the host in a way that is too large, we can get away with it with the PTS as it is not a production server and players are not concerned with their stats on it so much. The individual servers are not "franchises", each server is owned and operated by Wargaming.
Yes, all of these will carry over as they are available on all servers. Just because they haven't been utilized on the other servers doesn't mean they don't exist there.
Unfortunately, yes, you will have to start again.
We are not transferring clans.
You would need to download the ASIA client - a second version of the game.
In the past several modpacks have offered region selectors however this functionality is not officially supported.
Fem,