To get started with Android/katstalk, you'll need to get familiar with Git and Repo.
To initialize your local repository using the katstalk trees, use a command like this:
repo init -u git://github.com/katstalk/android.git -b kk44
Then to sync up:
repo sync
For more information on this Github Organization and how it is structured, please read the wiki article
All supported devices are built nightly and periodically as changes are committed to ensure the source trees remain buildable.