While it is good that revision is listed, without an actual date it is not straightforward to tell when was that revision (one needs to go to the extension source repository and cross reference).
It will be good to add a text that says Revision date just underneath it.
Good idea. This could be implemented in the new extension manager front-end. Please add a feature request at issues.slicer.org.
I also added another issue to suggest implementing an update mechanism for stable version’s extensions under the Manage Extensions.