The gaffer-dev mailing list is home to development discussions, feature requests, and is a great place to ask questions of the development team and wider user-base. Its archives contain a wealth of questions, answers, and examples accumulated over the years.
Each Gaffer release is posted as a thread on GitHub Discussions. We also encourage questions and general discussion there.
Presentations, examples, and demonstrations can be found at the GafferHQ Vimeo.