Couple of Roman questions

As the Rome release is going to come soon(er), I have a couple questions about the Rome civilization.

First off, how many mercenaries are they going to be able to hire? I would think that, considering the enormous ethnic diversity of their empire, they would have the lion's share of hireable mercs to serve as Auxilia in their legions. :2thumbsup:

Second, while I know that Res Gestae is thankfully eliminating a number of fiction units (Arcani, Flaming Pigs, Repeating Ballista), the historical Roman army did use light ballistic weapons like ballistae. However, the ballistae in the game are hardly worth anything, while the real Romans used them to good effect! Is there going to be any incentive in R.G. to use lighter ballistic weapons than just spamming Onangers?