Hello
To subscribe for the sub server, firstly you need to buy crystals. Unlike gPotato you can write the amount you'd like to purchases. You can then use those crystals to buy subscription from this page:
http://en.allods.com/subscription
There is a full FAQ here
Sub Server FAQ and the English forum section dedicated to the sub server is here
Sub Server Forum Section The server itself is international so there are many different languages spoken, but there is always a strong English presence on both servers and with current attempts to revive things I'm certain you will find English speaking players to play with. The sub server has been merged with the old NA sub server. It's now located in the Netherlands.
Allods is now being published by my.com. It is the international version of mail.ru and belongs to them.
Also, you can choose to hide the other language forums and display only the English ones.
Go to Edit Profile --> Management --> Forums on/off and simply un-tick those that you do not wish to see.
I hope this answered your questions