Android ProgressBar with custom indeterminate drawable is quite easy to achieve. This tutorials shows how to do it.
Adding padding to a RecyclerView might not turn out as you expected. Fortunately it's easy to fix with clipToPadding attribute.
How to setup signing config in Gradle and handle keystore loading without adding secrets to version control
Change Gradle settings and output apks with more descriptive filenames.
Android Application class gives the developer a nice way to initialize dependant libraries and other features.