You can run CUCM as "out of compliance" for up to 60 days when you don't have enough licenses, it will just show a warning when you login (this applies to all license types, not just TP room licenses).
Expressway is required if you want to conference with other organisations over the internet but is not required for conferences within your own LAN/WAN.
it only needs a VCS if you want to use it in conjunction with being able to make external "URI calls".
have you got a standalone unit. in which case you might want to consider registering it with webex cloud instead
You will need a Webex account, and from the Webex Control Hub, you should be able to generate an activation code for your endpoint to register to your Webex org. Enter this code on to endpoint in the setup wizard, and it will work with your Webex There are some good instructions on how to do that in the Collaboration Help site here: How Do I Add an Endpoint in the Cisco Webex Control Hub?