I think that the staging would not have been that appropriate as there were no skenes and therefore no 'off stage'. It would be difficult for the audience to suspend their disbelief for the duration of the play when characters would be onstage but not involved in the action. Similarly it would be difficult for the actors to remain in role at all tiemes when on stage and to be on stage but not involved at all.
ii. I think that the characters at the beginning of the play would be near the altar and temple as the Eumenidies begins in the tample of Apollo and therefore it would make sense to place the actors near a religious temple.
iii. The chorus could have performed higher up nearer the audience perhaps to represent that they are higher more godly beings but segregated from the religious world of the real Gods (auch as Apollo).