There are many avenues to recieve help when using the Coherence Incubator. Here are a few options.
The Discussion Forums for the Coherence Incubator are the best place to start asking questions - should you need to. These forums are hosted by Oracle and are typically monitored by the community.
They can be found here: https://forums.oracle.com/forums/forum.jspa?forumID=558
To participate in the discussion forums you will need an oracle.com account.
As all of the source code, including tests and examples are now published, these are often a great place to start for implementation tips.
The source code is located here: https://github.com/coherence-community/coherence-incubator
If you find an issue with the Coherence Incubator or have an idea for a new feature the best place to start is with the Issue Tracking System. All issues, both current and past are publicly viewable.
The Issue Tracking System can be found here: http://java.net/jira/browse/COHINC
To raise new issues you will need a java.net account (these are free).
Alternatively Oracle Coherence customers can file Support Requests (SR) against the Coherence Product, clearly specifying that requests are for a Coherence Community project.