I've had a fun game with my ancestors even took Rome after 100 turns them praetorians are tough but it was very rewarding to crush the senate and the brutii, the scipii and julii are holding out on the islands to the west .How to do that easy take the balkans as quicly as posiible ally with scythia and germany.
i can help you with some questions ,mentioned previously in this thread
Why the dacians have balistas?because they have been in contact with the greeks and romans for quite some time and are more "civilized" then most other barbarians.
As for the cavalry most of the dacian cavalry were actually allied cavalry roxolan,carpian,yazighian,iashian cavalrymen sarmatians at origin but quickly assimilated into the dacians.