By default, the LaTeX output uses the class article. You can
change this by adding an option like #+LaTeX_CLASS: myclass in your
file. The class must be listed in org-latex-classes.
Embedded LaTeX as described in Embedded LaTeX, will be correctly
inserted into the LaTeX file. Similarly to the HTML exporter, you can use
#+LaTeX: and #+BEGIN_LaTeX ... #+END_LaTeX construct to add
verbatim LaTeX code.