[Rivkin]

Unfortunately, I can't find my books (so I have to apologize for not oftering references _yet_), so I have to rely on memory and Britannica:

Salahadin (himself a kurd) was from the family of atabegs - Turk-seljuk warlords, who were supposedly "protecting" Baghdad Caliphat. With time this family and its seljuk's was becoming more and more powerful.

In 1169 Salahadin marched into Cairo, slaughtered around 40,000 black mamluks (Nubians etc.), their families, disbanded other parts of Cairo garrison and replaced it with his seljuks.

Concerning Salahadin's "white" mamluks he was the first one to introduce them into Egypt. Till that time only seljuks used to purchase slave boys from Caucasus and Kipchak territories (eventually stretching from Khorezm to Hungary), and put them into service as "guard" units. With Salahadin this practise was greatly expanded, mostly through buying kipchaks from Cuman Kipchak regions (Modern Crimea and Ukraine) and northern caucasus kipchaks.

Concerning the languages he spoke - it's certain he did speak arabic, I did not see the movie, but it seems natural for him to use arabic as a diplomatic language.

Now concerning languages that were used by mamluks among themselves in general it was always their own language - turks spoke turkish dialects (kipchak), mongols I think spoke kipchak too,
georgians spoke kartli, adighas- adighe, other caucasians (armenians, chechens etc.) spoke usually adighe or kartli, depending on which one was dominant.

Concerning that only kipchaks and circassians were mamluks - Ali-Bey, Mehmed Beg and most of post XVII century mamluks were georgians (megrel tribe, western georgia), some of prominent mamluk leaders before were Mongol or Seljuk. It's important that in arabic literature word "cherkes" can mean anything from around Caucasus.

It's interesting that mamluks were so isolated in their national community that very often they did not develop any islamic identity (great example is Rustam's memoirs and to some extent famous correspendence of XIX century mamluks with russian tzar and georgian kings).