Deploy new version of existing application on FUSE Fabric

We are planning to use Fuse Fabric (Fuse ESB 6.3) to deploy applications.

What would be the deployment process for releasing a new version of an existing application?
We are looking for an approach by which we can deploy and validate a new version of the application, while the current version is still running.
Once verified, the new version of the application will replace the old one, on each node (one at a time).
The existing documentation for the FUSE ESB 6.3 version does not provide much details in this regard.

Additionally, how to access REST DSL Service from Fabric Gateway ? Does it work only for Apache CXF services?