Here is the spec: http://www.seeedstudio.com/depot/datasheet/2088RGBMatrix.pdf
I think they should be quite similar but not exactly the same. We tried 3.3V, it worked fine too. 5V is too bright for close look.
For the current calculation, you should divide it by the frequency if dynamic scan. They are not lit 100% time or 100% output, the actually result should be well below 20ma each.
Let me measure the actual current consumption and post the result later.