New character required, or can we play this with existing?

[CodeMage]

You’ll need to create a new character and there is no transfer of characters or inventory from one map to another:

Seperate map or Linked?

Hey there, To clear any confusions. To play on Siptah, you will need a new savegame/database. they are not linked, but separate maps. However, as part of that update, we’ll be adding the option to swap between those maps when loading a game, meaning you won’t lose progress on the Exiled lands or Siptah when playing on the other map.

The server can only run one map at a time, not both simultaneously.