Hello Johanna, 

I am using scimax from John Kitchin [[https://github.com/jkitchin/scimax
]]and I recommend it to you warmly. 

In my /user/user.el,  here is what is about beamer : 

#+BEGIN_SRC lisp

(add-to-list 'org-latex-classes
             '("beamer-ahp-ul"
               "\\documentclass\[10pt,svgnames,fragile]\{beamer\}
                [NO-DEFAULT-PACKAGES]
                [PACKAGES]
                [NO-EXTRA]
\\theoremstyle{plain}% default
\\newtheorem{thm}{Theorem}[section]
\\newtheorem{theo}{Théorème}[section]
\\newtheorem{lem}[thm]{Lemma}
\\newtheorem{prop}[thm]{Proposition}
\\newtheorem*{cor}{Corollary}
\\theoremstyle{definition}
\\newtheorem{defi}{Definition}[section]
\\newtheorem{rema}[thm]{Remarque}
\\newtheorem{Conjecture}[theorem]{Conjecture}
\\newtheorem{exa}{Example}[section]
\\newtheorem{exem}{Exemple}[section]
\\\hypersetup{colorlinks,
citecolor=blue,
linkcolor=.,
menucolor=white,
filecolor=pink,   
anchorcolor=yellow
}
\\AtBeginSection\[\]\{\\begin\{frame\}<beamer>\\frametitle\{\}\\tableofcontents\[currentsection,hideothersubsections\]\\end\{frame\}\}
\\subtitle\{\}
\\institute\[Université de Lorraine\]\{Département de philosophie \\\\ Archives Henri Poincaré - UMR 7117 du CNRS \\\\ Université de Lorraine \\\\ 91 bd Libération, 54000 Nancy \\\\ France \}
\\titlegraphic\{\\includegraphics\[height=1cm\]\{ahp\}\\includegraphics\[height=1cm\]\{udl\}\\includegraphics\[height=1cm\]\{cnrs\}\}
\\usetheme\{CambridgeUS\}
\\usepackage\{beamer_udl_theme\}
\\setbeamertemplate\{navigation symbols\}{%
	%insertslidenavigationsymbol%
	%insertframenavigationsymbol%
	%insertsubsectionnavigationsymbol%
	%insertsectionnavigationsymbol%
	%insertdocnavigationsymbol%
	%insertbackfindforwardnavigationsymbol%
}
\\setbeamertemplate{theorems}[numbered]
"
               ("\\section\{%s\}" . "\\section*\{%s\}")
               ("\\subsection\{%s\}" . "\\subsection*\{%s\}")
               ("\\subsubsection\{%s\}" . "\\subsubsection*\{%s\}")))

(require 'autoinsert)
(auto-insert-mode)  ;;; Adds hook to find-files-hook
    (setq auto-insert-directory "~/MEGA/org/my_org-templates/") ;;; Or use custom, *NOTE* Trailing slash important
(setq auto-insert-query nil) ;;; If you don't want to be prompted before insertion
(define-auto-insert "\.beamer-fr.org" "beamer-fr.org")

#+END_SRC

in   my  folder   ~/MEGA/org/my_org-templates/  there   is  the   file
beamer-fr.org:

#+BEGIN_SRC lisp
#+TITLE: 
#+DATE:
#+OPTIONS: H:2 toc:nil author:t
#+LATEX_CLASS: beamer-ahp-ul
#+LANGUAGE:fr



** 
:PROPERTIES:
 :BEAMER_opt: allowframebreaks,label=
:END:
bibliography:/home/joseph/MEGA/org/reforg.bib
bibliographystyle:apalike

#+END_SRC

I have  also defined a  theme that  corresponds to my  institution and
that                  is                   located                  in
/home/joseph/texmf/tex/latex/local/beamer_udl_theme.sty 

Now,  as  soon  as I  write  a  file  that  ends with  the  expression
"beamer-fr.org", it is  immediately with this template  and the export
beamer works smoothly.

I have nothing with notes, but I hope it helps. 

Best wishes, 

Jo.