It looks like we are getting more Dwarfs. There is Bossy and Watchy and it looks like we get Stealthy back so this is before Snow met the Dwarfs when Stealthy gets killed.
And it looks like Belle will be back in the episode for a cameo of some sort though i think that episode is mostly about the dwarfs and Grumpy and his love interest. I am not sure if Belle being in the episode suggests this happens during the time that she is stuck with Rumpel or after or before. I guess we need more information to guess at that.
I also think it is interesting that the Blue Fairy may be the head fairy and the other fairies work under her. I think that is interesting to have the fairies have a hierarchy.