Hi. The file "Interop.WSManAutomation.dll" is included with the Intel AMT DTK. It's just a .NET wrapper file for accessing WinRM and yes, if you use IAmtTerm you now need it because I started adding WSMAN support.
As for the serial agent menu, if you use IAmtTerm.exe in TCP mode (like Telnet) that menu is made invisible, but will show up if Intel AMT Outpost or Intel AMT Guardport is present on the Intel AMT computer. Just press the ` key to make it show up. I did this because platforms such as Intel SCS plug-in use IAmtTerm.exe and don't want customers to use these features.
Hope this helps,
Ylian (Intel AMT Blog)