Never see a requirement like that but, for management traffic it depends on what services are you using, vSAN, vMotion, Replication, etc.
With 1GB that it's usually the minimum it should be enough in most environments but, it really depends on the environment and services running.
Unless I am wrong, I believe vCenter just orchestrates. When stuff has to go from host A to host B, it really goes from A to B, without (much) touching the vCenter box.
What's more important is how your hosts are cabled up.
Most branded servers will have at least 2 Physical Adapters, simply patch cables on all of them to the switch on your rack.
VMware Support Staff says, "configured both the nics in "Route based on originating Virtual port" Load balancing method which is perfect for performance and load balancing."
I've done all sorts of bandwidth intensive tests, it all seems the same.
Unless you are doing something really intense, of which at that level you'll also know how to dedicate connections with a recipe for vSwitches and VM Networks.
Until then, just pipeline them all together equally. You'll most likely be satisfied as I was.
That is a very open ended question, there are various vCenter performance documents out there that give some level of detail: