Hello and welcome to the Kontalk forum.
For the server part, we are in the process of testing our new Docker container instance:
As a matter of fact, our test instance is already running on Docker and it's working quite well. The production instance will soon migrate to Docker too. We strongly suggest you use that and provide feedback if needed because support for the manual installation process will be dropped soon. The installation procedure is pretty straightforward and it's very easy with the help of the Docker tools.
As for the clients, do you intend to create a commercial product out of it? If you are willing to open source it, it would be nice if we can collaborate in the creation of clients for other platforms, especially iOS, so both projects could benefit from them. Also, you will have our full support and guidance on development if you choose to contribute back to the Kontalk community.