No, the Oly site says "Participating Dealers" so I assume you would not get the cashback.
As far as low light performance is concerned, it is quite possible that the CaNikons have better performance, the question is, is the Oly adequate? One major benefit is the in body stabilisation, and of course the compact lenses help too, so you can effectively shoot at a lower ISO.
My experience with an OM-10 MkII is that I very very rarely come up against any low light deficiencies, I had to look through archives to come up with a grainy shot. Here's one, streetlit in India, shot at ISO1600 using the 17mm cheapie pancake lens, which just happens to be forum suitable (click for bigness), that's as bad as I've got.