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

\usepackage[columnsep=1cm,lmargin=1cm,rmargin=1cm,tmargin=1.5cm,bmargin=1.5cm,bindingoffset=.75cm]{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}{0pt}{0pt}{-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

\twocolumn
\thispagestyle{empty}
\input{articles/impressum.tex}\newpage
\input{articles/adressen.tex}
\newpage\thispagestyle{empty}
\input{articles/editorial.tex}\newpage
\section*{Inhalt}\tableofcontents
\newpage

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

\Hide\chapter{Vor dem Studium}\thispagestyle{fancy}
\input{articles/vor_das_richtige_studium.tex}\newpage
\input{articles/vor_einleitung_bac.tex}\newpage
\input{articles/vor_medieninf.tex}\newpage
\input{articles/vor_medzinf.tex}\newpage
\input{articles/vor_se.tex}\newpage
\input{articles/vor_ti.tex}\newpage
\input{articles/vor_inskription.tex}

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