I would think they should be released a separately as the qt dependency changes the nature of the licenses being depended on, and a more free main branch would be preferable.
Qt is available under a commercial license, the LGPL, and the GPL. Can you elaborate on your concerns?
It is just that. It would be the most restrictive license yet used for anything required. If this was brought in, anyone distributing binaries will also have to make available the source code to the Qt that they used for example or not bundle it. Wxwidgets made sure those conditions did not apply to derived works distributed in binary form. The creators of Qt got dragged a bit towards it even being as unrestricted as the LGPL in the beginning. I had noticed that the licenses picked so far are all much less restrictive and had thought that was a deliberate choice to keep the software free to more uses without the burdens of the GPL