This is a very nice article that I recently have followed. The licensing piece is definitely a miss in the article, but is part of the cluster setup in my mind.
The one thing that I did that isn't mentioned in the article, IIRC, is that I created a new witness appliance, then after I moved the hosts to the new vCenter and new Cluster, I changed the witness host to the new appliance. I don't remember having any issues, but, I would do some testing before doing this with a live production cluster, or open a proactive SR and request them to validate the steps against your environment. That's actually what I did and it was great to have the eyes on before doing anything, and having the SR already open and ready incase something went sideways.
