Is 1 cup of rice powder equal to 1 cup of uncooked rice?
I agree with your evident suspicion that 1 cup of whole rice will not be the same amount of rice as 1 cup of rice flour. There would be quite a bit of air in the cup with the whole rice, and not in the cup of rice flour. To get an equivalent amount of "rice-matter", you really need to use weight measurements.

But aha!... Look at this handy-dandy rice unit converter
           http://www.traditionaloven.com/conversions_of_measures/rice_amounts_converter.html  

(somebody had too much time on their hands)

Anyway, I tried it out, and according to them, 1 cup(USA) of rice => 185 g => 6.5 oz.

So if you want to get an amount of ground up rice equivalent to 1 cup whole kernels, try 6 and a half oz. ... But, as Catija &amp; GdD point out in comments, the two rice products, even if materially equivalent, aren't going to act the same at all, so be very wary, ready to adjust your amounts empirically, and don't expect your first attempt at this dish to impress critical people.