Will the app drain my phone battery and data capacity?
The app does not use much energy. To check if you have been near other CoronaMelder users, the app uses Bluetooth Low Energy. This form of Bluetooth consumes very little power. The exact percentage of your battery used by the app will depend on your phone.
The app uses data a few times a day to find out if you have been close to another person who is infected. For that purpose, the app compares the codes on the server with the codes you have exchanged via Bluetooth. Those codes will be stored on your phone for 14 days. To prevent unwanted data costs, you can set the app to use data only when you have a Wi-Fi connection. No data will be lost; the app will simply exchange data at a later point in time.