When you setup your publication as a booklet, the pages  are presented in the
correct order automatically. The half pages will be portrait.

Have you tried to setup a booklet? If you have, what problems are you
experiencing?

If you are trying to print 2 copies of the same thing on the page (which you
will cut apart later), set up your page size to the size of the page you want
to end up with. (5.5" wide by 8.5" high).  You will then be given a printing
option to center the smaller page on the large sheet of paper which is
specified in the printer properties OR to print multiple copies on the page.  
Obviously you want multiple copies.

If you actually want a booklet, there is a page set up option for precisely
that.  Select it and it will take care of the rest.  Including managing to
get the right pages in the right places when it is printed - even for
multiple pages with duplex printing.