hello (I know, its been about four months...)
Soon, I will be trying this too. Those collections and Vortex are working well wit FNV, for me.
To add a non-Nexus mod in Vortex, you should probably use the "Install from File" button, top left, mods pane. As long as the archive is structured correctly, the mod should then enter your build just like all the others. If the archive is not so well put together, you may have to adjust its file structure manually.