Thanks for your input!
I decided to go for the URL in case someone wants to hide the transmitter behind a reverse proxy. Also the URL is provided by the device itself, so in case they change the base URL with a firmware update, the plugin would continue to work.
Well, the file can be downloaded somewhere from the ZMote web app. The idea was to make it as easy as possible for the user. The user can configure his buttons with the web app and then just use the downloaded file as input for the binding. But I guess I could add a configuration parameter for direct IR codes as well.
That will not be included in the initial version of the plugin, as it is handled by the ZMote web app (see above). However if it turns out that there really is a need for it, I can implement it.
For now I just try to get an initial version ready so I can actually test it when my device arrives.
Thank you!