These are all great questions for Epson. As I responded to your other post, asking how much ink is used in the Initial Fill, I don't know for sure but would guess about 20-30ml per channel (to move ink from carts to the print head). I couldn't guess the ink consumption of the regular or power clean cycles, and the nozzle check uses just a tiny bit of ink. If Epson has a good response for you, we'd be curious to know what you find out.
Best regards~ Dana