This will depend a bit on which Container Adapter type you're using, Managed vs Remote. Bu tyou are correct, there is a disconnect here.
For the Remote adapter, we simly don't have access to the container configuration, so you'll need to tell the adapter where it should connect.
As for the Managed adapter, both 1 and 2 are possible options. The question is more, who is in control.
Arquillian is the one that starts the container, so it might be logical to look at 2.
Unless you run against a predefined configuration(you possible have other code relying on the mgm ip/port), then 1 is a better option.