use [master]

GO

GRANT ALTER ANY CONNECTION TO [**USER**]

GO

use [master]

GO

GRANT VIEW SERVER STATE TO [**USER**]

GO

You can run SP_who2 with "View Server State" permissions.

grant ALTER ANY CONNECTION to USER, will allow you to kill user sessions.

Take a look at these links for example powershell scripts. To schedule the task add a new job step using powershell as the type.

http://community.spiceworks.com/scripts/show/1480-powershell-script-delete-x-days-old-files-from-a-folder-days-and-file-types-can-be-changed

http://gallery.technet.microsoft.com/Powershell-script-to-ed34c5f9

Does your maintenance plan fail? You could add a powershell step to the job to remove files older than 7 days.