New here, question

[brais]

Which server should i choose? (looking for pve)
And whats the xp rate?

[AverageJoe]

Nostalrius Begins is the only realm you can select as the rest are all test realms for beta players and developers. There is no PvE realm at the moment.

And everything is 1x. You should read some of the sticky threads in the Announcements forum; they answer these types of questions.
https://forum.nostalrius.org/viewtopic.php?f=2&t=3