@Kelly The available virtual cores you can assign to a particular VM match the number of logical threads(for hyperthreading) on the nodes. If you have identically spec'd nodes there will be no restrictions put in place beyond that for the number of virtual CPUs you can assign to a particular VM.
The limit of number of virtual cores to the smallest amount of logical threads is specifically to prevent issues with over-provisioning so there are automatic limits put in place to prevent issues that would cause VMs to not be stable.
I'm really glad to hear you are purchasing a cluster and we look forward to working with you.