From a fresh install of Kubuntu 11.10, attempting to update your software through the “Software Updates” dialog will fail due to lack of permissions. To resolve this, run
sudo apt-get install polkit-kde-1
The Software Updates dialog will then correctly ask for an administrator password so it can make changes to the system.
Checking the files installed by a package is easy enough with the Synaptic package manager (Right-click package > properties > installed files tab).
Here’s how to get that information without leaving the comfort (cough) of your bash terminal:
$ dpkg-query -L package_name
$dpkg-query -L flashplugin-installer