RTW Campaign with BI exe - a few questions

[Ciaran]

I know you can start the Imperial Campaign via the BI exe, but how?
And then there are a couple of other issues: Will phalanxes still work, since I don´t know yet whether any BI unit has phalanx capability? And what about the Marius Reform and the Senate (those are really important), does all the Senate-related stuff (missions, offices, Senate and population ranking and so on) still work and the reforms still happen?

This doesn´t look much like modding questions, but the main issue is using a couple of BI features like swimming or the Schiltron in an Imperial Campaign or rather a provincial campaign that is based on the Imperial Campaign.