Saves should all go fine and behave like they do for the SD card/RAM launched stuff. It should even share it with the one on the SD card if for some reason you decide to flit between the two. or more likely delete it from the NOR for whatever reason.
Figuring it out. It is much the same as their earlier carts and I have been staff on or otherwise involved with the English speaking support forums for quite some time
http://ezflash.sosuke.com/
Not sure what there is for a guide at this point. I was sent a sample of the new one to review but it is mostly as it was then it hit however many years ago so I was going to write a guide and edge cases type review. On edge cases and fixes/workarounds then
http://gbatemp.net/threads/buying-a-gba-flash-cart-in-2013.341203/page-18#post-4756995 will hopefully get you somewhere.
There once was an English version of the help file on there but if you have installed the newer kernels I think the EZTeam put it back to Chinese and with all the updates we did not make everything nice and easy to sort version of it all again.