Yes Tom, pages turn correctly from right to left on iOS and even on Mac (using the mouse). Pages also turn automatically when the feature "Turn My Pages" is enabled. This was supported a little bit more than a year ago (can't remember which version of iBook app), but probably after iOS9 was rolled out, and I stumbled on it by pure chance.
To make this happen, simply set the page-progression-direction to "rtl" in the spine of your .OPF file
<spine page-progression-direction="rtl">
As for the correct display of Arabic text, the correct value for the direction will take care of it.
Example: <body dir="rtl">
I'm very discouraged by the iBookstore policy concerning RTL languages such as Arabic/Hebrew etc.., and I am trying to push for a change. I have been working for a while on an educational initiative to disseminate children Arabic books to Syrian/Iraqi/Libyan/etc.. refugees scattered in camps in the Middle East, and as asylum seekers and immigrants in Europe and NA, but the project was shelved for that reason.
Please refer me to any one who could help.