You should be able to directly installed sp3 but make sure to take backup of instance and clean uninstall is not supportedhttps://helpx.adobe.com/experience-manager/6-3/release-notes/sp3-release-notes.html#WhatsincludedinAEM6330
If you are referring to the project https://github.com/adobe/aem-sample-we-retail-journal I havent seen any issue ( aem 6.4 + sp2)What I am wondering is your bundles are not in active state for we.retail journal, can you double check them?
OOTB notifications are sent to the person who upload the assets.You would have customize the implementation for emails.https://helpx.adobe.com/in/experience-manager/6-3/assets/using/drm.html#Assetexpiration
Are you trying to update package details like name, description, group from external application. Make sure to provide login-token or authenticate with repositoryMore details will be helpful.
1. Can you attach the package for community?2. Did you try Troubleshooting steps herehttps://helpx.adobe.com/experience-manager/kt/sites/using/getting-started-wknd-tutorial-develop/part6.html#Troubleshooting
I am not clear on the issue, probably some screenshot may help.Meanwhile if its an urgent customer related project, request you to reach out day care team from adobe
You can use content services from aem to get the CF here is a demo with react apphttps://helpx.adobe.com/experience-manager/kt/sites/using/content-services-tutorial-use/part7.html