The official website of the Acceleo project can be found here: http://www.eclipse.org/Acceleo It is the best place to find all the information about the Acceleo project, including where to download the latest version of Acceleo and links to the forums, the documentation and videos about Acceleo. You can also find a lot of resources on the Acceleo wiki: http://wiki.eclipse.org/acceleo
You can find in this documentation a small tutorial to help you with the creation of your first Acceleo project. You have also access to the complete documentation of the Acceleo language. You may want to have a look at the Acceleo examples (File -> New -> Examples) in order to understand the basic concepts used in Acceleo. Finally, you can also find an open source UML to Java code generator on Github that you can checkout, fork and contribute to.
On the Obeo Network, you can find a complete user guide for Acceleo with lots of screenshots and dozens of videos presenting all the features of Acceleo. You can also find videos from presentations of Acceleo for different conferences.
You can find a guide with all the good practices written by the Acceleo development team on the Obeo Network.
The Acceleo community can be found on the Obeo Network with a group dedicated to Acceleo users. You can also find all the latest news about Acceleo on twitter. Finally, you can find the blog posts of the member of the Acceleo community on planet acceleo.
Acceleo creates a Java class as the entry point of the generation for each modules with a main template. You can use this Java class to launch the generation from Eclipse or in stand alone (without any dependencies with Eclipse). You can also create an Ant task file or a Maven file to launch the compilation of your generators (right click on an Acceleo project -> Configure). You can also find an Ant task to launch the generation in the "/tasks" folder of your Acceleo project. You can find an extensive documentation for the integration of an Acceleo generator in an Ant, Maven or Java based workflow in the Acceleo 3.1.0 User Guide on the Obeo Network.
If you have a problem, you can post your problem on the official forum for Acceleo and all the Model to Text software of the Eclipse foundation here: http://www.eclipse.org/forums/index.php?t=thread&frm_id=24&
You can also contribute there by answering to the questions of other persons.
The Acceleo team can be contacted through the official Eclipse M2T forums and newsgroup. Yet this form of support may not meet daily needs of an enterprise adopter as far as response delays are involved. Most of the developpers of Acceleo are from Obeo, and are then the best source to provide competent and professional support.