A new MW extension repository (mediawiki/extension/PushNotifications) was created for push notifications. It won't be used; we're putting the MediaWiki bits in Echo instead. The extension repo should be archived.
Yes, that's the one. I don't think we're quite ready for this to happen yet, though; there's still a patch open on it in Gerrit. I just wanted to get this task filed to track that it should happen.