To see all the files the package installed onto your system, do this:
dpkg-query -L <package_name>
To see the files a .deb file will install
dpkg-deb -c <package_name.deb>
To see the files contained in a package NOT installed, do this once (if you haven't installed apt-file already:
sudo apt-get install apt-file
sudo apt-file update
then
apt-file list <package_name>
See this question for more