Is possible modifying this font to have only the "normal" s and u also in the doubles ?

\documentclass[pagesize=auto, version=last]{scrartcl}
\usepackage{fontspec}
\usepackage{microtype}
\defaultfontfeatures{Ligatures=TeX}
\setmainfont[RawFeature={+ss02,+cv01,+ss05,+dlig},ItalicFeatures={RawFeature=+cv04,CharacterVariant=5:2}]{EB Garamond}
\newfontfamily\booktitlefont[LetterSpace=40,WordSpace=2,RawFeature={+ss02,+cv01,+dlig}]{EB Garamond}
\newfontfamily\spacedfont[LetterSpace=20,WordSpace=3,RawFeature={+ss02,+cv01,+dlig}]{EB Garamond}
\begin{document}
\begin{itemize}
\item pression
\item s
\item u
\item bassun
\end{itemize}
\end{document}
microtypefeatures including\lsstyledon't work with XeLaTeX. For using the font in equations see this question: Selecting main math font in LuaTeX (The answers will work for XeLaTeX as well.) – Alan Munn Jul 17 '12 at 21:07fontspecdocumentation, where the commands you are using are all explained. You can usetexdocto look at package documentation. See this answer http://tex.stackexchange.com/a/63359/2693 for how to use it in Windows. – Alan Munn Jul 17 '12 at 21:47\setmathfont{lmmath-regular.otf}. See theunicode-mathdocumentation for more information. – Alan Munn Jul 17 '12 at 22:41