Hi Frank,
I've been a little busy with projects to spend a long time on answers here.
Just to help us all, in the future, could you separate your questions into topics?
Mainly because I primarily help with Velbus integration, any other answers I might give are just things I've discovered along the way.
So, to address your questions, as best I can...
Z_Wave commands vs Velbus commands.
I can only tell you that the OpenRemote controller talks to a TCP server app on the BeagleBone which handshakes the commands to and from a USB connection to a Velbus network.
In practise, this Velbus Server could be on a totally different computer. I have tested 3 simultaneous connections to separate Velbus networks without any major issues.
We have a project in the pipeline which will see a rack server version of OpenRemote communicating with >118 Velbus TCP servers.
I assume that Z-Wave works in a similar way, but I suggest you look for a Z_Wave expert for more help. (of which there are quite a few)
Camera streams.
At first I thought that the OR Controller processed the stream before sending it to a client, so I configured some test WebElements with local URLs.
This worked well while the clients were on the same local network.
As soon as I tried to connect off-site, the WebElements failed to display.
Using an external URL solved that problem.
I must conclude that the client device handles the WebElement content directly.
I'm told that in recent versions of the Android app and WebConsole, clicks within the WebElement areas are passed to the web content, allowing for interaction.
For the record, I have't had a need to test this yet.
As for discounting the price of the Din Rail controller instead of offering a buy back, I can't do that for many reasons.
Regarding migrating your project from OR_2.1 to OR_2.5, please follow the pinned topics for more information.
As for creating a beautiful UI, I use the services of graphics designers for my clients, I would be happy to ask them to quote for your project.
And finally regarding Sonos, although I've tested it briefly with a BBB, I don't own any Sonos hardware so I would be reluctant to pre-install the server purely because I have no way of confirming that it works before I shipped the controller to you.
I hope that helps.
Good luck,
Stuart