About the first initial landing page
The first page is the first main menu entry. In other words: The initial page is the page in the first menu level with the lowest "page order" number.
There is no separate "settings" for setup a other "landing page".
To change the page order go to:
- edit page -> change page order
Note: You can't use a plugin page as a initial landing page, yet. (see also: issue 30)