Settings/Reading Settings/Reading/Landscape Layout. You can choose two-page or single page layout there.
Nope, you can not.
I do not have this option.
I can choose between Portrait, Landscape or automatic. But this all does not have any influence whether it is split or not.
I do not have the option to choose between single or double page layout
FYI I have taken a pic of the available settings
This might help also.
I am running Version 3.1.1211