I am afraid that the only mention of Mauryan Empire was to deny that they would be a faction (although the team has left open the possibility of a Mauryan Satrapy as faction). As for your other questions:
1) "Finishing moves" are part of the animation engine, so they will be included. However, I expect the team will make them realistic and toned-down rather than theatrical.
2) No, see the link I gave above.The team wants all factions to be playable.
4) EB1 included Alan and Scythian units: these will most likely make it to EB2 as well. I don't think we will be seeing them as factions, though.
5) All EB1 factions will be included. We may even see more Celtic factions.
I don't know the answer to 3 and 6.