Import-Module ServerManager itself didn't work for me on my windows 2008 Server. I found that its only available by default on Windows 2008 R2, and you need to install Exchange elsewhere.
Looking at alternatives and ActiveDirectory module seems good but again I think ActiveDirectory powershell modules are not available unless you have AD Domain Service running on your Server for which you WFA server itself will need to be a Domain Controller ( dcpromo ) which is cumbersome and not even required. If anyone can suggest otherwise, then please help.
I see its easier to enable Powershell Remoting on Active Directory and then invoking commands to AD server to query for results. Powershell Module ActiveDirectory will be available on your Domain Controller. Ypu can see it as "Start-> Administrative Tools -> Active Directory Modules for Windows Powershell" to verify.
On AD server : Enable-PSRemoting
Select A for all choices.
Now from your WFA server you can invoke commands to query for users etc.