The only time you would want to use the recovery file (.rec) is when you are executing a multi-phase graph and at least one phase has completed. You can then use the .rec file to restart the graph from the most recently completed phase.
However, you should only use the rec file if something external to the graph caused failure. Examples of this are: network going down, shared disk becoming unavailable or something similar. If you have a bug in your code and that cause failure, then you'll want to use m_rollback to remove both the rec file and any intermediate files ab initio created and start over.
Ab Initio does not publish their manuals, you will have to contact Ab Initio directly for materials.