In last days, and thanks to the discussions with my mentors, through IRC, mumble, and emails, I got a good start with the project.
First I successfully setup a Debian chroot environment in order to test, package and develop. 
Next, I've tried to build an app using only the packaged android-SDK, this process helped me to spot multiple bugs that I that I reported (problems about JDK, Gradle, aapt, fastboot...).
Reporting this bugs helped either open discussions about them and explain the issue and try to understand them, or, fix them by committing patches to my fork on gitlab, review them, then push them to Alioth.
While working on all of this, I also learned many things about Debian developing and maintaining and more understanding the manuals that I've already read and put this knowledge to practical cases.
This few days my experience with Debian has grown a lot ! and I feel more excited than ever to work on this project !