A few questions...

5 hours ago, ldoodle said:

I know how to create Dynamic Device Groups and have done one for Active Directory hosts using the hasCategory("MicrosoftDomainController") custom query. I would like 2 more dynamic groups, one for Microsoft DHCP and one for Microsoft DNS. I'm not sure what Category to use for each.

If there isn't a distinct category for DHCP and DNS, you'll need to somehow create them. Easiest route would be to use a PropertySource to query the device to find out if it serves DNS and/or DHCP and set the appropriate categories that way. Then it would be trivial to make the dynamic groups.

5 hours ago, ldoodle said:

How do I lock each Customer dashboard to just their own AD hosts? The LM guide uses an example if the MSP has a standardised naming approach for servers. We don't. The customer names their servers to suit their own naming convention

You should have each customers' devices sorted into groups already. When you create roles for those customers, you'll need to limit those roles to just those groups. 

5 hours ago, ldoodle said:

We are monitoring vCenter (VCSA). The default dashboard is pulling some info in but most of it is NaN. How do I resolve these NaN issues?

Check here that you've added the credentials properly. Follow the link to get more detail on how to monitor vCenter here.