ARD has a separate password for each user, even if it's the same copy of the app running from the same mac. Make sure the serial number and installation is done under the ladmin account. Also check in ARD (under an admin) that the preference for non-administrators has the other users of the Software present. It should prompt for an ARD password when logged in as a user, rather than a serial/pass.
You will need to attach the plist preference files for Office 2011 in the relevant group within workgroup manager's 'details' tab. If 2011 is replacing 2008, then you can simply replace the 2008 plist file with the 2011 ones. If you're keeping 2008 on any machines at all, then you will need to create a new group solely for the new machines having 2011 on them.
Just seen the top bit is mentioned almost exactly already, but I'll leave it there anyway now I've typed it all