patch repository and quilt patches should be same patches with different formats, getting patches from patch repository is recommended. All the patches can also be found from ext4 git tree.
The patch queue series is divided into stable and unstable patches. The stable patches are the one usually the ones used to push back upstream, while the unstable section has the patches for development purposes only and are not ready for pushing upstream (and some may never make it in). File series marks status of each patch.