In the specs I found:

* Software console for monitoring, metering, and setting levels
* Built-in digital mixer provides near-zero latency monitoring
* Supports Windows Me/2000/XP/Vista (32-bit and 64-bit) and Macintosh OS X (Jaguar, Panther & Tiger)
* Supports pro audio software (WDM Kernel Streaming, ASIO, GSIF (32-bit only), and CoreAudio)
* 8 "Virtual Outputs" - run multiple applications at the same time
* Low-latency drivers

So I don't think you'll have a problem with running BiaB and EWI USB Aria at the same time.
As for the technogeek-bit: Don't worry.
In BiaB you can go to the audio preverences and select the ASIO Echo WDM driver. Now you can choose which virtual outputport you want BiaB to use. Since the Aria-software is likely to use the default (0,1) you can set BiaB to use (2,3).
I don't know MIDI Yoke, so I can't give you any accurate information on that software. But if you can select an audio output within that program, you can set it to use (4,5). This way every program uses a different virtual output and you'll hear everything at the same time coming from the mini-jack

Mike
www.mikewever.nl