holly_x For app list syncing, I think Play Store may have a way to do this. If not, Tasker should be able to do it. You'll need to periodically export your list of apps to a server or cloud storage, periodically check if that list was modified, find the differences, and install/uninstall apps based on it.
If you want to update apps, just let your app manager do it unattended, it's the most simple and straightforward.
I don't think anything generic for writing app data is doable without root.