\documentclass[10pt,a4paper,twoside,openright]{book}
\usepackage[absolute]{textpos}
\usepackage{paralist}
\usepackage{multicol}
\usepackage{hyperref}
\usepackage{graphicx}
\DeclareGraphicsExtensions{.pdf,.png,.jpg}

\usepackage[columnsep=2cm,lmargin=1cm,rmargin=1cm,tmargin=1.5cm,bmargin=1.5cm,bindingoffset=1cm]{geometry}

\usepackage[explicit]{titlesec}
\newcommand*\Hide{%
\titleformat{\chapter}[display]
  {}{}{0pt}{\Huge}
\titleformat{\part}
  {}{}{0pt}{}
}

\usepackage{etoolbox}
\makeatletter
\patchcmd{\chapter}{\if@openright\cleardoublepage\else\clearpage\fi}{}{}{}

\makeatother
\titlespacing*{\chapter}{-40pt}{-40pt}{-40pt}

\usepackage{fancyhdr}
\pagestyle{fancy}
\lhead{}
\chead{}
\rhead{}
\cfoot{}
\renewcommand{\chaptermark}[1]{ \markboth{#1}{} }
\fancyhead[LE,RO]{\leftmark}
\fancyfoot[LE,RO]{\thepage}

\makeatletter
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}{-6ex\@plus -4ex \@minus -2ex}{.1mm}{\normalfont\normalsize\bfseries}}
\makeatother

\makeatletter
\setlength{\@fptop}{0pt}
\makeatother

\makeatletter
\renewcommand\tableofcontents{\@starttoc{toc}}
\makeatother

\usepackage[perpage]{footmisc}


\begin{document}\thispagestyle{empty}
\begin{textblock*}{\paperwidth}(0mm,0mm)\noindent\includegraphics[width=\paperwidth,height=\paperheight]{images/cover_front.png}
\end{textblock*}
\mbox{}\newpage

\begin{multicols}{2}
\thispagestyle{empty}
\input{articles/impressum.tex}\columnbreak
\input{articles/adressen.tex}
\newpage\thispagestyle{empty}
\input{articles/editorial.tex}\columnbreak
\section*{Inhalt}\tableofcontents
\newpage

\Hide\chapter{Einleitung}
\input{articles/einleitung_die_fsinf.tex}\newpage
\input{articles/einleitung_beratung.tex}\newpage

\Hide\chapter{Vor dem Studium}
\input{articles/vor_das_richtige_studium.tex}\newpage
\input{articles/vor_einleitung_bac.tex}\columnbreak
\input{articles/vor_medieninf.tex}\newpage
\input{articles/vor_medzinf.tex}\columnbreak
\input{articles/vor_se.tex}\clearpage
\input{articles/vor_ti.tex}\columnbreak
\input{articles/vor_inskription.tex}
\end{multicols}

\mbox{}\newpage\thispagestyle{empty}
\begin{textblock*}{\paperwidth}(0mm,0mm)\noindent\includegraphics[width=\paperwidth,height=\paperheight]{images/cover_back.png}
\end{textblock*}
\end{document}
