Hi and welcome to the community!
First licenses: Is everything subscription based with recurring fees, or is the software single purchase with optional support contracts or the like?
There are several types of licenses:
1. Perpetual License
(based on the number of CPU sockets in your virtualization host(s))
Products do not expire, support does. One year of basic support and maintenance is included with any new perpetual license purchased. Assuming that you have 2 sockets in each host you'll need to get license for 2 x 2 = 4
2. Subscription License
(based on the number of CPU sockets in you virtualization hosts)
At the end of the license period, both the use of the product as well as support will be turned off. Customers can choose to purchase a new subscription license at the then-current rate or buy a new perpetual license.
There are also other types, for more details please visit this FAQ
To protect physical endpoints
in a free mode you don't need a separate license for physical machines - the abovementioned license located on Veeam Backup and Replication (VBR) server will let physical machines to place backups onto Veeam repositories. However, if you want to use advanced features of Workstation/Server versions then you'll need to purchase a separate license for physical hosts, one per physical machine, because VBR does not allow mixing of free and paid physical backups within the same VBR instance.
Of these, I have 11 of them that I want to back up on a regular basis (daily or every few days) at least. I'd prefer to do more of them, but that will depend on budget.
The rest I'd like to have a less frequent backup for, perhaps once a month or once a quarter, if licensing doesn't "get in the way" (more on that below).
License does not put any restrictions on how often you perform backup, you can even backup the machines every 15 minutes.
Apart from the licenses, I'd like to know if I can manage everything from a central location - managing clients, schedules, set backup locations, backup retention time etc.
All these features will be introduced in the next version of VBR