What is the relationship between hook_cron() and hook_cron_queue_info()?
The relationship is they are 2 independent hooks that can be used in conjunction with one another depending on what the task is. 


hook_cron(): Provides a means to supply a custom function to respond to a cron event.
hook_cron_queue_info(): Provide a means to supply queue metadata for a cron event that will need a queue (i.e. any task that can't be fully processed in the limited time during a cron event).


In your example above:


Yes revision_scheduler_cron is adding to the queue. 
But no, revision_scheduler_cron_queue_info is not processing the queue, it's providing the function (revision_scheduler_operation_process) to call for processing and how long (revision_scheduler_cron_time) it should be allowed to execute for processing.