here is good to start article https://scug.be/blogs/sccm/archive/2011/08/11/download-the-latest-evaluation-software-to-build-your-private-cloud-with-system-center.aspx
Datacenter or Enterprise editions to look at Hyper-V
Free Server just Hyper-V No Windows Server (Free)
VMware , Hyper-V or Xen can both be managed by this current product
The 2012 version of SCVMM . A better way to manage any virtualization and can work with different fabric.
Known as SCOM helps you monitor what’s going on real time with your operations
Known as SCCM, The product that helps you roll out clients or servers and properly configure them and baseline them.
The next version of SCCM which is really a brand new product.