Optimal Virtual Sever Requirements for Windchill\Intralink

I have been FINALLY giving the go ahead with our upgrade from Intralink 3.4 to Windchill\Intralink.

Would like to get the ball rolling by requesting our IT-Group to supply properly configured Virtual Servers.

May ask for your recommendation:

1. What is preferred operating software to install on, “Sever 2012 R2”?
2. What would recommendation for quantity of RAM, 16 to 24 GB?
3. Is VMware the preferred visualization software?
4. What did I forget to ask?

Thanks in advance,

Robert