Setting the date position to the top right in a NF.lco (french style) scrlttr2

With the suggestion below you can still use \setkomavar{date}{...} and \setkomavar{place}{...} and you can enable/disable the usage of fromphone and fromemail using options fromphone and fromemail, respectivly. If variable place is empty, the place seperator will be removed.

Note, that the contents of variable firsthead overwrittes both option fromalign and fromlogo. To remove the back address you can set option backaddress=false. Do not change \parskip manually, use option parskip instead.

\documentclass[a4paper,11pt,french]{scrlttr2}

\usepackage{palatino} 
\usepackage[T1]{fontenc}
\usepackage{babel}
%\usepackage[utf8]{inputenc}% not needed with an uptodate TeX Distribution
\usepackage{eurosym} 
\usepackage{geometry} 
\usepackage{graphicx} 
\geometry{verbose,a4paper,lmargin=3cm,rmargin=3cm}

\KOMAoptions{parskip=half-}%<- do not set \parskip manually

\usepackage{setspace}
\setstretch{1.15}

\usepackage{url}% <- added

\LoadLetterOption{NF}%

\KOMAoptions{%
  %fromalign=center% <- no effect because of \setkomavar{firsthead}{...}
  ,fromphone=true
  ,fromemail=true
  %,fromlogo=true% <- no effect because of \setkomavar{firsthead}{...}
  ,backaddress=false% <- remove backaddress
  ,refline=nodate% <- remove date from the refline
  ,subject=titled% <- use a title for the subject
}

\renewcaptionname{french}{\subjectname}{Objet}% like your lettre version
\addtokomafont{subject}{\normalfont}% <- like your lettre version

\renewcaptionname{french}{\ccname}{C.c.}% like your lettre version
\setkomavar{ccseparator}{}
\setkomavar*{ccseparator}{\llap{\ccname\quad}}% like your lettre version

\setkomavar{placeseparator}{, le }

\setkomafont{fromname}{\scshape}
\setkomafont{fromaddress}{\small}

\setkomavar{emailseparator}[E-Mail]{~:~}% <- like your lettre version
\setkomavar{enclseparator}{ > }
\setkomavar{fromaddress}{7-13 rue dejourney\\  49000 ANGERS}
\setkomavar{fromemail}{\url{[email protected]}}% <- like your lettre version
\setkomavar{fromname}{Gigiair}
\setkomavar{fromphone}{0123 456 789}
\setkomavar{phoneseparator}[Tél]{.~}% <- like your lettre version
\setkomavar{place}{Angers}
\setkomavar{signature}{\hspace{26em}\includegraphics[width=2.5cm]{example-image}}% <- changed
\setkomavar{subjectseparator}{~:~}% <- like your lettre version
\setkomavar{subject}{Modèle}

\makeatletter
\setkomavar{firsthead}{{%
  \usekomafont{fromaddress}%
  \parbox[b]{\useplength{firstheadwidth}}{%
    {\usekomafont{fromname}\usekomavar{fromname}}
    \hfill{\usekomafont{placeanddate}%
      \ifkomavarempty{place}{}{\usekomavar{place}\usekomavar{placeseparator}}%
      \usekomavar{date}%
    }%
    \\\usekomavar{fromaddress}%
    \medskip% similar to the lettre version
    \if@phone\\\usekomavar*{fromphone}\usekomavar{fromphone}\fi
    \if@mobilephone\\\usekomavar*{frommobilephone}\usekomavar{frommobilephone}\fi%
    \if@fax\\\usekomavar*{fromfax}\usekomavar{fromfax}\fi
    \if@email\\\usekomavar*{fromemail}\usekomavar{fromemail}\fi
    \if@www\\\usekomavar*{fromurl}\usekomavar{fromurl}\fi
  }}%
}
\makeatother

\begin{document}

\begin{letter}{\`A Madame la centurion\\
    Camps de Babaurum\\
    Bretagne conquise}
\def\concname{Objet :~} 

  \opening{Madame la centurion,}
  C'est une invitation pour manger du sanglier roti.
  \closing{à la tienne !}

  \cc{Panoramix et Obleix}
\end{letter}
\end{document}

Result: