including font in .otf

Question

I'm writing my thesis at a company and have to write it in their default font.

How can I set a .otf font in Latex (using Texmaker on Windows)?

\documentclass[a4paper,12pt,twoside,ngerman]{article}
\parindent0pt
\parskip6pt
\usepackage{fontspec}
\fontspec [Path = fonts/,
    UprightFont = *-Light,
    ItalicFont = *-Thin
 ]
{AkkoPro}

\begin{document}

hello world

\end{document}

Latex throws an error:

! LaTeX Error: File `expl3.sty' not found.Type X to quit or <RETURN> to proceed,or enter new name. (Default extension: sty)Enter file name:! Emergency stop.<read > \usepackage

How can I install expl13? Is the way to include fonts correct? My fonts are in the "fonts" folder in the same directory like the .tex File and are called AkkoPro-Light.otf and AkkoPro-Thin.otf. Is it possible to include fonts for Bold and others? (I've got AkkoPro in Bold, Light, Medium, Regular and Thin...)

I found a lot about xetex and luatex, but I don't know, what it is...

Sorry for my terrible english =)

---

I solved the font problem by using

\setmainfont[Path = fonts/,
BoldFont = AkkoPro-Bold.otf,
ItalicFont = AkkoPro-Thin.otf,
BoldItalicFont = AkkoPro-Light.otf
]{AkkoPro-Regular.otf}

but now I´ve got a lot problems by the other packages and commants...

When I'm using the utf8 inputenc package, there will be an error in the header "!Missing \endscname inserted".

\pdfinfo

is now called "undefined control sequence"

\begin{figure}
    \includegraphics[width=0.5\linewidth]{images/logo.jpg}
\end{figure}

in Line using \includegraphics XeLaTeX throws the error "!Dimension too large. ...

all these errors appears by using \setmainfont and disappears by deleting this command...

My header:

\documentclass[a4paper,12pt,twoside,ngerman]{article}
\parindent0pt
\parskip6pt

%%%%%%%%
%Pakete%
%%%%%%%%
\usepackage{fontspec}
\setmainfont[Path = fonts/,
BoldFont = AkkoPro-Bold.otf,
ItalicFont = AkkoPro-Thin.otf,
BoldItalicFont = AkkoPro-Light.otf
 ]{AkkoPro-Regular.otf}


\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel} % Paket für die neue deutsche Rechtschreibung
\usepackage{bera}
\usepackage{color}
\usepackage{xcolor}
\usepackage{listings} % Packet zum Erstellen von Listinings

\definecolor{lightgray}{HTML}{F3F3F3}

\colorlet{jsonPunct}{red!60!black}
\definecolor{jsonDelim}{RGB}{20,105,176}
\colorlet{jsonNumber}{magenta!60!black}

\definecolor{lightgreen}{HTML}{3F7F5F} % comments
\definecolor{purple}{HTML}{950055} % keywords
\definecolor{lightblue}{HTML}{3F7DE0} % javadoc
\definecolor{turquoise}{HTML}{5FC0C0}
\definecolor{darkblue}{HTML}{2A00FF}
\lstdefinelanguage{json}{
literate=
 *{0}{{{\color{purple}0}}}{1}
  {1}{{{\color{purple}1}}}{1}
  {2}{{{\color{purple}2}}}{1}
  {3}{{{\color{purple}3}}}{1}
  {4}{{{\color{purple}4}}}{1}
  {5}{{{\color{purple}5}}}{1}
  {6}{{{\color{purple}6}}}{1}
  {7}{{{\color{purple}7}}}{1}
  {8}{{{\color{purple}8}}}{1}
  {9}{{{\color{purple}9}}}{1}
  {:}{{{\color{purple}{:}}}}{1}
  {,}{{{\color{purple}{,}}}}{1}
  {\{}{{{\color{darkblue}{\{}}}}{1}
  {\}}{{{\color{darkblue}{\}}}}}{1}
  {[}{{{\color{darkblue}{[}}}}{1}
  {]}{{{\color{darkblue}{]}}}}{1},
}
\lstset{
language=Java,
keywordstyle=\color{purple}\bfseries,
commentstyle=\color{lightgreen},
morecomment=[s][\color{lightblue}]{/**}{*/}%,
}
%XML Style
\lstdefinelanguage{XML}
{
  morestring=[b]",
  morestring=[s]{>}{<},
  morecomment=[s]{<?}{?>},
  stringstyle=\color{black},
  identifierstyle=\color{turquoise},
  keywordstyle=\color{purple},
  morekeywords={android, name}% list your attributes here
}
% Allgmeiner Style für Listings
\lstset{
basicstyle=\footnotesize,
tabsize=2,
numbers=left,
numberstyle=\scriptsize,
stepnumber=1,
numbersep=8pt,
showstringspaces=false,
showspaces=false,
backgroundcolor=\color{lightgray},
frame=none,
rulecolor=\color{black},
aboveskip=1em,
belowskip=1.5em,
captionpos=b,
breaklines=true
}
% die folgendenen 3 Pakete sichern, dass Wörter nicht so oft am rechten Rand herausragen
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{microtype}
\usepackage{graphicx} % Paket zur Verwendung von Bildern. alternatif epsfig
\usepackage[
colorlinks=true,
linkcolor=magenta,
anchorcolor=black,% Ankertext
citecolor=green, % Verweise auf Literaturverzeichniseinträge im Text
urlcolor=cyan, % Farbe der URLs
backref % Back-Links zu den Kapiteln
]{hyperref}
\usepackage{floatflt} % Paket Bildpositionierung
\usepackage{marvosym} % Paket zur Verwendung von manchen Sonderzeichen
% Paket zur Verlinkung des Inhaltsverzeichnisses, als (vor-)letztes laden (es muss zweimal compiliert werden), nur glossaries muss danach geladen werden
\usepackage{fancyhdr} % Paket für den Pagestyle fancy
\usepackage{dirtree} % Paket zum Erstellen einer Verzeichnisstruktur
\usepackage[
nonumberlist,   %keine Seitenzahlen anzeigen
acronym         %ein Abkürzungsverzeichnis erstellen
]{glossaries}
% Entfernt den Punkt am Ende der Beschreibung beim Glossar
\renewcommand*{\glspostdescription}{}
%sammelt die Einträge
\makeglossaries
%%%%%%%%%%%%%%%%%%%%%%%%%%
%Allgemeine Informationen%
%%%%%%%%%%%%%%%%%%%%%%%%%%
\title{Titel}
\date{}
\author{}
\pdfinfo{
  /Title    (Titel)
  /Author   (me)
  /Creator  ()
  /Producer ()
  /Subject  ()
  /Keywords ()
}