Is there a recommendations on how you should structure and configure a multisite environment with EPiServer? Any articles on the subject?
Here do you have all the guides and technotes http://world.episerver.com/Documentation/Categories/Products/EPiServer-CMS/.
I you're thinking about multiple sites in the same solution, you can read about it here http://world.episerver.com/Documentation/Items/Tech-Notes/EPiServer-CMS-6/EPiServer-CMS-60/Enterprise---Configuration/
Multiple sites in the same solution is what I want. I looked at the documentation you refer to, but I don't have an "Add Site" button. Do I need a special enterprise developer licence for that?
Yes you need a "EPiServer CMS 6 Enterprise Partner Developer License".
You could also add the sites manually in episerver.config and episerverFramework.config.