A Feast for Crows will revolve around the happenings of the Southern regions of Westeros. This will include Kings Landing, Dorne and the Iron Islands. As for characters featured, pretty much all of the ones in previous books (minus the dead and undead ones) and one or two new ones. So thats Jaime, possibly his sister as well, Tyrion probably will not feature in Feast (More likely in Dance) and that leaves room for some new ones.
A Dance of Dragons is mostly the North and other lands. So thats Arya, Bran, Jon, Dany and Tyrion.
I don't know how long publishing takes but Dance is more than half way done, so hopefully we will see another in the near (errr semi-near depending on GRRM's work schedule) future.
Hope that helps.