And now I can definitely confirm all of the above. I went to a nearby Target today and I was surprised to find that they had jumped the gun and had put Nemo out two weeks early.
As you can see, yes, Nemo indeed has the two Power Discs, and yes, they have a 3.0 stamp on them. No sign of Dory or the Play Set, so unless they sold out early, they hadn't been put out yet.