Internal (to the NAS) backup

Excuse my (possibly) ignorant question.

I am attempting to establish a Rsync backup job that copies data between two different volumes on the same NAS. 

Question #1

Using a loopback approach (127.0.0.1) my guess is that will be more efficient relative to time and system resources.   Is that a reasonable guess?

Question #2

Using 127.0.0.1 as a destination address will apparently specify a loopback address.  Using this approach my assumption is that the data will be processed internally without any attempt to send out over the attached LAN.  Can this approach used with the ReadyNAS GUI exposed version of Rsync?

The alternative is apparently to have a ‘local’ backup job defined with the designation of a different share on a different volume within the same NAS.  Is this the equivalent of the loopback approach in terms of efficacy?

Question #3

Rsync has many options; certainly more than our staff is capable of dealing with without some type of GUI.  It seems that most of those options are not implemented in the ReadyNAS GUI version of backup.  Is there a way to expose them or alternatively is there a different backup application that could be used that has some type of GUI along with more of the options?  In particular we are looking for some incremental or differential version of a backup job.