I am curious as to what your Egyptian drummer can tell you--The piece used for Bellydance is really a classical turkish or arabic form that includes a song, a couple Taqsim, at least two distinct rhythms, as well as a couple of makams for improvisation--

All of the records that include extended pieces for Bellydancing use this structure, so you can actually just sit down and count it all out, and you''ll have the structure to work with--

Makams (or Maquamat) are not simply scales, each has it's own set of rules for improvising, which you would learn from a classical master--

Perhaps you will excuse my skepticism, but I find it hard to believe that you have acquired any sort of mastery of Arabic and Turkish scales simply by ear--the music tends to be very complex, and is an intellectual effort, as much as anything--It is best to keep this in mind when you approach a master--

I would go to an Arabic or Turkish club, where the musicians know what they are doing, and talk to them about who the masters are, and how to find them--There are a lot of people around who fudge there way through--