Sylius is a Open Source project driven by the community. Join our amazing adventure and we promise to be nice and welcoming to everyone. Remember, you do not have to be a Symfony guru or even a programmer to help!
You can learn how to contribute the patches and how we use Behat & PHPSpec in two separate parts of our Contributing Guide.
Sylius is not stable yet, but has been already used in production and we treat security very seriously. You can read about security procedures here.