Hey Max, yes they work together. But you're not able to get to JSF-UI through WebUI. If you have both addons installed you can access JSF-UI by entering following URL:
<Nuxeo host>/nuxeo/nxhome/default/@view_home (s. Nuxeo 9.3 or 9.10 Platform not showing various tabs).
Works for me using the latest Docker image.
Yes. In LTS 2016, if both packages are installed, a button in the top menu of the JSF UI allows to switch UI