App should be able to download new data without need of update from Play Store

[met]

Up to now when we want to change some app data (dictionary, stories, sound, pictures...) we have to release a new app version.
We need to create a mechanism for updating app data without necesity to install new version.

Here is what I think we need to handle in the app side:

• App freshly installed from the store should not be empty, it need to contain enough data (now we have around 1500 vocabulary items, around 100 pictures, 9 stories - that all should be included in the installation if it doesn't break app size limit). So if the user just install app and even if he does not download any more data, the app should still be usefull. Maybe it will not contain all our content, but basically every screen/app-section will work, because has some basic data.
• App should periodically check for new data (once a day? - remember some users are not always connected to the internet) and app will inform user that it should update data (need to specify UX - maybe some icon always visible on user screen?) . There might be even text description available of what is new in the new data.
• App have possibility to check for new data on a user command
• App have possibility to download new data on a user command (we need to specify some UX for that), app will check data integrity and ignore them is something seems wrong.
• In case something got wrong (data corrupted) there should be an easy way to return to the basic settings (= app will use only the original data packed in the app installation and will ignore/delete downloaded data)

We also need to specifty what should be done on server side or data.movapp.cz or update.movapp.cz if we want to separate update web from data web.

Here is the same issue but for iOS app.