What filepermissions am I supposed to set?
You don't need to set some speciall permissions (though read-only for core forums are recommended), and installation process just warns
you your folder is vulnerable for some reason.
I added some forum - which then is in the dropdownmenu under "edit forum".
But I can't see it under index.php. Why could that be?
Try to set $startPageModern=FALSE;
in setup_options.php. Until you have not posted any kind of topics, new layout will hide the forums listing (because new layout is oriented on the forums which already have some topics, at least 10 or 20 so they could appear on the left side).
There is no "login" button for regular user - just "sign up". That can't be right either.
Login boxes should appear straight on the first page or under posting forms. Like you see on our forums here!