Finishing android app

I am looking for an android developer in the Grenoble region who can help finish an app that we built. The app is developed to communicate physiological measures via BLE to a server. The following was remarked by programmer friends from the US:
1)We need better documentation how to setup the dev environment. The original developer could help with this.
2) Related to (1), there are dependency issues (e.g., other libraries not working or specified) and ambiguities (e.g., a number of libraries that could be what is being referred to). These need to be resolved (again, original dev can help).

Once that is taken care of, we need the following:
- do some debugging of existing app.
- including an existing module to our app. The module is already programmed, but needs to be integrated into our app
- improve security protocol of our app (create one, essentially)
- improve aesthetics of the app
- create backend (ideally on Open Science Framework ([URL visible pour les membres Pro])) so that we can immediately visualize data that we collect.
- add option so that it's possible to see whether the phone is close to another phone of ours.