At the moment I have one host that I have to enable EVC for so that I can vmotion with all my other hosts (4 in total). My option is to create a cluster with EVC enabled and move all my hosts into this cluster. My question is what are the pros and cons of moving all my host into one cluster? Should I isolate the one host and allow vmotion to work with the other 3 hosts?
It all depends what your business/technical requirements are. For example, do you have a workload you would be willing to run on a single ESX(i) host that doesn't have the ability to vMotion? What will you do when you have to patch the ESX(i) host? Will you then shutdown your Virtual Machines? Do you have a need for an independent swing-server you can pre-test patches and changes on? Do you require an independent test lab environment? I can't see any technical reason why you wouldn't want to enable EVC on a new cluster and combine all your hosts to one cluster.
VCP 3, 4
Depending on your licensing:
Distributed Resource Scheduler (DRS)
Distributed Power Management (DPM)
the list goes on....
The information you are looking for can be found be browsing the VMware website and product documentation.
VCP 3, 4