I think, about the soundtrack, Rome II soundtrack should be the base for AE... Rome I music like a submod for nostalgics...
And Why? Mainly for campaign music, it feels more authentic to the theme.
I think in these tracks:
https://www.youtube.com/watch?v=w8VzrG3vRKM
https://www.youtube.com/watch?v=eOJSelhFfqc
https://www.youtube.com/watch?v=dRCL-3LcWhw
Or why not choose the most authentic tracks from Rome I, Rome II and Attila and do a mix?