The provided .deb packages aren't very compliant with Debian policy or the FHS and aren't very robust (e.g. compiled files in architecture-dependent locations). I'm a Debian Developer and I can fix that with the right information.
Yep. Not sure why /usr/share/spotify was chosen for the 1.0.x release. I have been wanting to fix it or just move all of it back to /opt/spotify, similar to how chrome is packaged, and how it looked in 0.9.x releases.
It is currently not packaged with normal dh tools, but instead with a one-liner from a tarball with fpm, so package validation is pretty bad.