When you install ESXi and vCenter, both default to a 60 day eval for the Enterprise Plus licensing level, so you would be able to test any feature assuming you have the infrastructure to support it.
Are you planning to use another physical host? You can create a cluster with Enhanced vMotion Compatability (EVC) which allows host with different CPU models (you can't mix Intel/AMD CPUs) to run in the same cluster. The VMs get a virtual CPU that is based on a CPU model that all hosts can support. That way you don't have to get another exact match to your existing server. For some features like HA you'll require shared storage. If you don't have a SAN you could run a virtual SAN for your testing.
You can also do this on a single host. You could create a couple of virtual ESXi servers, virtual vCenter host and a virtual SAN. You'd be looking at needing about 8 - 10 GB of RAM allocated just to that. You could then run a nested VM (it could be 64 bit depending on the CPU of your current host) which could be configured for vMotion, HA, etc. You can also do this on a powerful workstation or laptop running VMware Workstation.
