I've recently really taken a liking for oriental music (The soundtrack from 'Hero' is what got me ) and was wondering exactly what the theory behind it is:

What scales are most common?
What chord progressions/patterns/motifs are most common?
Which instruments are used?
What structure does the music like?
What about rhythm?

Basically, I want to know everything that would help me get to grips with the theory of Oriental music, and hopefully, have me soon attempting to compose it as well.

Any help is appreciated!