1. Actually it's not the phonegap-plugin-push responsibility since it has not idea which topic it needs to subscribe.
2. Yes the old plugin do that, like I said above the old plugin delegate everything to the native lib so it's used from there.
3. No we don't need/should use the old plugin instead of phonegap-plugin-push because of that.
4. It's not a bug on phonegap-plugin-push because it the UPS stuff