How to get proper kerning with XeTeX and special characters?

Question

I would love to switch to XeTeX to make use of my professional Adobe fonts that were shipped with Creative Suite 6.

I use MikTeX on a Win 8 machine, and TeXniXcenter + XeTeX.

However, kerning seems to an issue, especially with special characters, in my case German Umlaute.

Spacing seems wrong, at least for characters W+ü. Actually, on a sidenote, I don't understand why -- does not give me a long dash...

Here is my MWE (UTF8) and a screenshot showing the wrong kerning:

\documentclass{scrartcl}
\usepackage{fontspec}
\setmainfont{Minion Pro}
\usepackage{listings}
\begin{document}

Wäre -- Könnte -- Wüste

\end{document}