GitHub is used for the daily development of Thym as well as the external contributions. Thym uses HIPP for builds.
Bugzilla is used for planning and bug tracking
Thym does not yet have localization/externalization.
To make it more convenient a contribution guide exists in both wiki and Github.
User documentation is limited. However, Cordova project is well documented, Thym relies on Cordova documentation for the concepts and utilizes screencasts to explain how they work while developing with Thym.