About the performance of Mender server and the update file transmitting

I have built a demo server(git clone -b 2.0.1 https://github.com/mendersoftware/integration.git integration-2.0.1). Now in our project I want to know the performance of the demo server, such as the max number of device connected to the demo server…
I know there are other ways to built the server, for example: Hosted server, Enterprise server. So, compared to the demo server, what’s the difference about these server versions( Hosted server, Enterprise server and demo server) ? I still don’t know which server would be chosen in out project.
Furthermore, I use the Artifact tool to generate the update file, but how to transmit update file from server to device? I mean, what is the interface of update file transmitting from server to device?

Thank you for reply.